These are instructions for setting up git to authenticate with GitHub when you have 2-factor authentication set up. This authentication should be inherited by any GUI client you are using. These are intentionally brief instructions, with links to more detail in the appropriate places.
Download and install the git command-line client (if required).
Open the git bash window and introduce yourself to git (if required):
git config --global user.name 'Firstname Lastname'
git config --global user.email 'firstname.lastname@example.org'