##Two references that tell you almost every useful git command:
https://services.github.com/on-demand/downloads/github-git-cheat-sheet
http://ndpsoftware.com/git-cheatsheet.html
##How to update your fork when upstream updates happen
git checkout master
git fetch class
git merge class/master
git push origin master
##How to fix things if you screw up and work on master:
git checout -b new-master class/master
git branch -m master test-branch
git branch -m new-master master
git status
git branch
git checkout test-branch
git status
git branch set-upstream to=class/master test-branch
git rebase
git rebase
git status
git push origin <name of current branch>
On Github: check the pull requests