This is tutorial how to setup a drupal 7 site with git but without putting drupal core into git, reason is that you don't need it in git unless you are patching core. As drupal core is always the same and updated with drush, version control is not needed at least there is a stream of opinion that goes into that direction. So what do you do, you only put sites folder into git. Let say you want to clone it locally from remote repo. Steps to follow would be, first clone that repo where you have only sites directory and then you copy drupal core to that directory, with having .gitignore file that also ignores all the core files (you can get that file attached to this post). And from there you install drupal and commit only what you need to to sites folder.