When you do Source Control -> Commit, you can check the checkbox, Push to remote, at the bottom left corner to also push to your remote repository.
https://github.com/jh1ood/libsndfileXcode/commits/master
You can always compare the different file versions with the menu: View -> Version Editor -> Show Comparison View. By clicking the clock-shaped icon in the middle, you will have a GUI similar to Time Machine.