diff --git a/.gitignore b/.gitignore
index 8d6a243f..451dd5dc 100644
--- a/.gitignore
+++ b/.gitignore
@@ -51,6 +51,7 @@ build-iPhoneSimulator/
 
 # Ignore environemnt variables
 .env
+.DS_Store
 
 # Ignore cassette files
 /specs/cassettes/
diff --git a/lib/channel.rb b/lib/channel.rb
new file mode 100644
index 00000000..8bb8988d
--- /dev/null
+++ b/lib/channel.rb
@@ -0,0 +1,37 @@
+require "dotenv"
+Dotenv.load
+require "httparty"
+
+class Channel
+  attr_reader :channel_name, :id, :topic, :members, :member_count
+  BASE_URL = "https://slack.com/api/channels.list"
+  TOKEN = ENV["SLACK_API_TOKEN"]
+
+  def initialize(channel_name, id, topic, members)
+    @channel_name = channel_name
+    @id = id
+    @topic = topic
+    @members = members
+    @member_count = members.length
+  end
+
+  def self.get
+    query = {
+      token: TOKEN,
+    }
+    channel_info = HTTParty.get(BASE_URL, query: query)
+    if channel_info["ok"] == false
+      raise ArgumentError, "The error code is #{channel_info.code} and the reason is: #{channel_info.message}"
+    end
+    return channel_info
+  end
+
+  def self.list
+    channel_info = Channel.get
+    channel_list = channel_info["channels"]
+    channels = channel_list.map do |channel|
+      Channel.new(channel["name"], channel["id"], channel["topic"]["value"], channel["members"])
+    end
+    return channels
+  end
+end
diff --git a/lib/slack.rb b/lib/slack.rb
index 960cf2f7..8b9af819 100755
--- a/lib/slack.rb
+++ b/lib/slack.rb
@@ -1,11 +1,67 @@
-#!/usr/bin/env ruby
+require "dotenv"
+Dotenv.load
+require "table_print"
+require "httparty"
+require "colorize"
+require_relative "workspace"
+require_relative "user"
+require_relative "channel"
 
 def main
-  puts "Welcome to the Ada Slack CLI!"
+  work_space = Workspace.new
+  puts "Welcome to the Ada Slack CLI!".colorize(:color => :blue, :mode => :bold)
+  puts "\nPlease Choose from the following options:\n1. List Users\n2. List Channels\n3. Select User\n4. Select Channel\n5. Details\n6. Send Message\n7. Quit".colorize(:color => :blue, :mode => :bold)
+  choice = gets.chomp.upcase
 
-  # TODO project
-
-  puts "Thank you for using the Ada Slack CLI"
+  until choice == "QUIT"
+    if choice == "LIST USERS"
+      puts "\n"
+      tp work_space.users, "username", "real_name", "id"
+    elsif choice == "LIST CHANNELS"
+      puts "\n"
+      tp work_space.channels, "channel_name", "id", "topic"
+    elsif choice == "SELECT USER"
+      puts "Here is a list of users:".colorize(:color => :magenta)
+      tp work_space.users, "username", "id"
+      begin
+        puts "Please enter a username or Slack ID:".colorize(:color => :blue, :mode => :bold)
+        user_input = gets.chomp
+        user_recipient = work_space.select_user(user_input)
+      rescue ArgumentError
+        puts "The username or SlackID is invalid."
+      end
+    elsif choice == "SELECT CHANNEL"
+      puts "Here is a list of channels:".colorize(:color => :magenta)
+      tp work_space.channels, "channel_name", "id", "topic", "members"
+      begin
+        puts "Please enter channel name or Slack ID:".colorize(:color => :blue, :mode => :bold)
+        channel_input = gets.chomp
+        channel_recipient = work_space.select_channel(channel_input)
+      rescue ArgumentError
+        puts "The channel name or SlackID is invalid."
+      end
+    elsif choice == "DETAILS"
+      begin
+        tp work_space.show_details
+      rescue ArgumentError
+        puts "There is no recipient selected. Please select a user or a channel."
+      end
+    elsif choice == "SEND MESSAGE"
+      puts "Please enter your message below:"
+      user_message = gets.chomp
+      begin
+        work_space.send_message(user_message)
+      rescue ArgumentError
+        puts "The message is invalid. Please try again."
+      rescue NoMethodError
+        puts "Message failed to send. Please select a recipient and try again."
+      end
+      puts "Your message was successfully sent to the recipient!"
+    end
+    puts "\nWhat would you like to do next?\n1. List Users\n2. List Channels\n3. Select User\n4. Select Channel\n5. Details\n6. Send Message\n7. Quit".colorize(:color => :blue, :mode => :bold)
+    choice = gets.chomp.upcase
+  end
+  puts "Thank you for using the Ada Slack CLI!".colorize(:color => :green, :mode => :bold)
 end
 
-main if __FILE__ == $PROGRAM_NAME
\ No newline at end of file
+main if __FILE__ == $PROGRAM_NAME
diff --git a/lib/user.rb b/lib/user.rb
new file mode 100644
index 00000000..70fa2971
--- /dev/null
+++ b/lib/user.rb
@@ -0,0 +1,36 @@
+require "dotenv"
+Dotenv.load
+require "httparty"
+
+class User
+  attr_reader :username, :real_name, :id
+  BASE_URL = "https://slack.com/api/users.list"
+  TOKEN = ENV["SLACK_API_TOKEN"]
+
+  def initialize(real_name, username, id)
+    @username = username
+    @real_name = real_name
+    @id = id
+    @user_info = User.get
+  end
+
+  def self.get
+    query = {
+      token: TOKEN,
+    }
+    @user_info = HTTParty.get(BASE_URL, query: query)
+    if @user_info["ok"] == false
+      raise ArgumentError, "The error code is #{@user_info.code} and the reason is: #{@user_info["error"]}"
+    end
+    return @user_info
+  end
+
+  def self.list
+    user_info = User.get
+    user_list = user_info["members"]
+    users = user_list.map do |user|
+      User.new(user["real_name"], user["name"], user["id"])
+    end
+    return users
+  end
+end
diff --git a/lib/verification.rb b/lib/verification.rb
new file mode 100644
index 00000000..3061338a
--- /dev/null
+++ b/lib/verification.rb
@@ -0,0 +1,15 @@
+require "dotenv"
+require "httparty"
+Dotenv.load
+require "ap"
+
+BASE_URL = "https://slack.com/api/channels.list"
+query = {
+  token: ENV["SLACK_API_TOKEN"],
+}
+channel_info = HTTParty.get(BASE_URL, query: query)
+channel_list = channel_info["channels"]
+channel_names = channel_list.map do |channel|
+  channel["name"]
+end
+ap channel_names
diff --git a/lib/workspace.rb b/lib/workspace.rb
new file mode 100644
index 00000000..575951f6
--- /dev/null
+++ b/lib/workspace.rb
@@ -0,0 +1,76 @@
+require_relative "user"
+require_relative "channel"
+require_relative "slack"
+require "dotenv"
+require "httparty"
+require "table_print"
+tp.set User, :username, :id
+tp.set Channel, :channel_name, :id, :members, :topic
+Dotenv.load
+
+class Workspace
+  attr_reader :selected, :users, :channels
+
+  def initialize
+    @users = User.list
+    @channels = Channel.list
+    @selected = nil
+  end
+
+  def select_user(user_identifier)
+    selected_user = nil
+    @users.each do |user|
+      if user.username == user_identifier || user.id == user_identifier
+        selected_user = user
+      end
+    end
+    if selected_user == nil
+      raise ArgumentError, "That user is invalid"
+    else
+      @selected = selected_user
+      return @selected
+    end
+  end
+
+  def select_channel(channel_identifier)
+    selected_channel = nil
+    @channels.each do |channel|
+      if channel.channel_name == channel_identifier || channel.id == channel_identifier
+        selected_channel = channel
+      end
+    end
+    if selected_channel == nil
+      raise ArgumentError, "That channel is invalid"
+    else
+      @selected = selected_channel
+      return @selected
+    end
+  end
+
+  def show_details
+    if @selected == nil
+      raise ArgumentError
+    else
+      return @selected
+    end
+  end
+
+  def send_message(message)
+    post_url = "https://slack.com/api/"
+    token = ENV["SLACK_API_TOKEN"]
+    response = HTTParty.post(
+      "#{post_url}/chat.postMessage",
+      body: {
+        token: token,
+        text: message,
+        channel: @selected.id,
+      },
+      headers: {"Content-Type" => "application/x-www-form-urlencoded"},
+    )
+    if response["ok"]
+      return response["ok"]
+    else
+      raise ArgumentError
+    end
+  end
+end
diff --git a/specs/channel_spec.rb b/specs/channel_spec.rb
new file mode 100644
index 00000000..26274b33
--- /dev/null
+++ b/specs/channel_spec.rb
@@ -0,0 +1,39 @@
+require_relative "test_helper"
+require "pry"
+
+describe "Channel class" do
+  describe "Channel#initialize" do
+    it "initializes a Channel object" do
+      VCR.use_cassette("Channel") do
+        response = Channel.new("fur_babes", "1234", "pets", ["AUAIWFS"])
+        expect(response).must_be_instance_of Channel
+      end
+    end
+  end
+
+  describe "Channel#get" do
+    it "returns information from the API" do
+      VCR.use_cassette("Channel") do
+        response = Channel.get
+        expect(response["ok"]).must_equal true
+      end
+    end
+  end
+
+  describe "Channel#list" do
+    it "includes a known channel" do
+      VCR.use_cassette("Channel") do
+        response = Channel.list
+        expect(response[0]).must_be_instance_of Channel
+        expect(response[0].member_count).must_be_instance_of Integer
+      end
+    end
+
+    it "returns correct number of channels" do
+      VCR.use_cassette("Channel") do
+        response = Channel.list.length
+        expect(response).must_equal 3
+      end
+    end
+  end
+end
diff --git a/specs/test_helper.rb b/specs/test_helper.rb
index 81ccd06b..efe23561 100644
--- a/specs/test_helper.rb
+++ b/specs/test_helper.rb
@@ -1,15 +1,31 @@
-require 'simplecov'
+require "simplecov"
 SimpleCov.start
 
-require 'minitest'
-require 'minitest/autorun'
-require 'minitest/reporters'
-require 'minitest/skip_dsl'
-require 'vcr'
+require "minitest"
+require "minitest/autorun"
+require "minitest/reporters"
+require "minitest/skip_dsl"
+require "vcr"
+require "webmock/minitest"
+require "httparty"
+require "dotenv"
+Dotenv.load
+
+require_relative "../lib/slack.rb"
+require_relative "../lib/channel.rb"
+require_relative "../lib/user.rb"
+require_relative "../lib/workspace.rb"
 
 Minitest::Reporters.use! Minitest::Reporters::SpecReporter.new
 
 VCR.configure do |config|
   config.cassette_library_dir = "specs/cassettes"
   config.hook_into :webmock
-end
\ No newline at end of file
+  config.default_cassette_options = {
+    :record => :new_episodes,
+    :match_requests_on => [:method, :uri, :body],
+  }
+  config.filter_sensitive_data("<SLACK_API_TOKEN>") do
+    ENV["SLACK_API_TOKEN"]
+  end
+end
diff --git a/specs/user_spec.rb b/specs/user_spec.rb
new file mode 100644
index 00000000..b55f3a63
--- /dev/null
+++ b/specs/user_spec.rb
@@ -0,0 +1,44 @@
+require_relative "test_helper"
+
+describe "User class" do
+  describe "User#initialize" do
+    it "initializes a User object" do
+      VCR.use_cassette("User") do
+        response = User.new("Larry", "Truck", "1234")
+        expect(response).must_be_instance_of User
+      end
+    end
+  end
+
+  describe "User#get" do
+    it "returns information from the API" do
+      VCR.use_cassette("User") do
+        response = User.get
+        expect(response["ok"]).must_equal true
+      end
+    end
+  end
+
+  describe "User#list" do
+    it "includes a known User" do
+      VCR.use_cassette("User") do
+        response = User.list
+        expect(response[0]).must_be_instance_of User
+      end
+    end
+
+    it "User details are correct" do
+      VCR.use_cassette("User") do
+        response = User.list
+        expect(response[1].username).must_equal "amyesh08"
+      end
+    end
+
+    it "returns correct number of Users" do
+      VCR.use_cassette("User") do
+        response = User.list.length
+        expect(response).must_equal 3
+      end
+    end
+  end
+end
diff --git a/specs/workspace_spec.rb b/specs/workspace_spec.rb
new file mode 100644
index 00000000..937cbf39
--- /dev/null
+++ b/specs/workspace_spec.rb
@@ -0,0 +1,106 @@
+require_relative "test_helper"
+
+describe "Workspace class" do
+  describe "Workspace#initialize" do
+    it "initializes a Workspace object" do
+      VCR.use_cassette("Workspace") do
+        response = Workspace.new
+        expect(response).must_be_instance_of Workspace
+      end
+    end
+  end
+
+  describe "Workspace#select_user" do
+    it "selects a known user by username" do
+      VCR.use_cassette("Workspace") do
+        response = Workspace.new
+        response.select_user("ngocle")
+        expect(response.selected.username).must_equal "ngocle"
+      end
+    end
+
+    it "selects a known user by slack id" do
+      VCR.use_cassette("Workspace") do
+        response = Workspace.new
+        response.select_user("UH553UM7G")
+        expect(response.selected.username).must_equal "ngocle"
+      end
+    end
+
+    it "raises an Argument if user info is invalid" do
+      VCR.use_cassette("Workspace") do
+        response = Workspace.new
+        expect { response.select_user("tildee") }.must_raise ArgumentError
+      end
+    end
+  end
+
+  describe "Workspace#select_channel" do
+    it "selects a known channel" do
+      VCR.use_cassette("Workspace") do
+        response = Workspace.new
+        response.select_channel("general")
+        expect(response.selected.channel_name).must_equal "general"
+      end
+    end
+
+    it "selects a known channel by slack id" do
+      VCR.use_cassette("Workspace") do
+        response = Workspace.new
+        response.select_channel("CH41W659D")
+        expect(response.selected.channel_name).must_equal "general"
+      end
+    end
+
+    it "raises an Argument if channel info is invalid" do
+      VCR.use_cassette("Workspace") do
+        response = Workspace.new
+        expect { response.select_channel("starburst") }.must_raise ArgumentError
+      end
+    end
+  end
+
+  describe "Workspace#show_details" do
+    it "shows details of the selected channel" do
+      VCR.use_cassette("Workspace") do
+        response = Workspace.new
+        response.select_channel("general")
+        expect(response.show_details).must_be_instance_of Channel
+      end
+    end
+
+    it "shows details of the selected user" do
+      VCR.use_cassette("Workspace") do
+        response = Workspace.new
+        response.select_user("ngocle")
+        expect(response.show_details).must_be_instance_of User
+      end
+    end
+  end
+  describe "Workspace#send_message" do
+    it "can send a valid message to a channel" do
+      VCR.use_cassette("Workspace") do
+        response = Workspace.new
+        response.select_channel("general")
+        status = response.send_message("Hey I can post messages!")
+        expect(status).must_equal true
+      end
+    end
+    it "raise an argument error when a message is invalid(empty,nil)" do
+      VCR.use_cassette("Workspace") do
+        response = Workspace.new
+        response.select_channel("general")
+        expect { response.send_message("") }.must_raise ArgumentError
+      end
+    end
+
+    it "can send a valid message to an user" do
+      VCR.use_cassette("Workspace") do
+        response = Workspace.new
+        response.select_user("ngocle")
+        status = response.send_message("Hey I can post messages!")
+        expect(status).must_equal true
+      end
+    end
+  end
+end