Git Config Username and Email

For just one repo:

git config user.name "Your Name Here"
git config user.email your@email.com

git config user.name alrafi
git config user.name "Hafis Alrafi"
git config user.email hafisalrafi@gmail.com

For (global) default email (which is configured in your ~/.gitconfig):

git config --global user.name "Your Name Here"
git config --global user.email your@email.com