This was a good introduction into GitHub on Microsoft Virtual Academy.  The course name is GitHub for Windows Users

https://mva.microsoft.com/en-US/training-courses/github-for-windows-users-16749?l=Tt7XrFR9C_8906218963

Command line Cheatsheet

Click to access github-git-cheat-sheet.pdf

Good documentation

https://git-scm.com/

Good information on getting involved in open resource

http://www.hanselman.com/blog/GetInvolvedInOpenSourceTodayHowToContributeAPatchToAGitHubHostedOpenSourceProjectLikeCode52.aspx