First you need to add your ssh key to your deploy:
-Login to GitHub.
-In the upper-right corner, click your profile photo, then click Your profile.
-On your profile page, click Repositories, then click the name of your repository.
-From your repository, click Settings.
-In the sidebar, click Deploy Keys, then click Add deploy key.
-Provide a title, paste your public SSH key from workingdir/id_github.pub.
-Select Allow write access if you want this key to have write access to the repository. A deploy key with write access lets a deployment push to the repository.
-Click Add key.
-Delete the SSH key from your disk:
rm id_github*
Once you do that, I found a some documentation for generate credentials that maybe you can use.
for connect git account to google look this documentation and then you continue with the part of the git configuration
and for the part that you ask for the credentials find this documentation this is the Google credentials