Add guide for github forks

Author: JohnTurnerNIH

docs/HowToForkRepository.md

@@ -0,0 +1,15 @@
+# Forking a Github Repository
+
+Navigate to the github repository you would like to edit. For this example we are forking the NIGMS-Sandbox repository. Click on the fork button near the top, image below shows it
+
+![](../images/images_for_github_fork/ForkCommand.PNG)
+
+You can then choose where you would like this fork to be placed. If you are working on a small patch alone you can select your personal github otherwise move it to whatever organization 
+will work on the modifications. 
+
+![](../images/images_for_github_fork/CreateLocal.PNG)
+
+After you click create fork the repository will be copied to the location chosen and then openned in your brwoser
+![](../images/images_for_github_fork/final.PNG)
+
+From here you can make the modifications required to your forked copy and then use a pull request to request that the changes be merged into the original repository.