Find the commit you want to roll back to
git log
Tell git which commit you'd like to reset your local repo to
git revert --no-commit 1e58b1d7... HEAD
git commit
Now update the repositry in Github
git push
Tell git you want to edit global configuration
git config --global --edit
Add this line to the bottom of the file
[alias]
ca = !git add -A && git commit -av