Get started with hacktoberfest and make your first PR here
Simply add your full name and the link to your github profile to Participants.txt and maybe checkout the other people who've added their names and the open source contributions they've made so far by visiting their profiles.
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Other additional useful links:
Learn what exactly is GitHub here: https://devbae.tech/git-it-p1/
Or watch this: https://youtu.be/w3jLJU7DT5E
Don't forget to register for Hacktoberfest: https://hacktoberfest.digitalocean.com
Download GitHub CLI here: https://cli.github.com
Look at simple issues you could help resolve, here: https://www.firsttimersonly.com/