When 2337 looked into GitHub, I was recommended
Pro Git by Scott Chacon (which is free), and was tremendously useful. I found the GitHub help to be useful when dealing with GitHub, but not with Git itself, the version control system.
As well, the GitHub for Windows client is very poor and not well-written. Frankly, my first ever experience with bash scripts (command-line) was with Git, and it was eye-opening. I highly recommend using Git bash.