All GUI clients for GIT you can find here. For Windows user I highly recommended open source client Git Extenshions.
If you want to contribute take this 5 simple steps for 5 minutes:
git clone https://github.com/__your_account__/sqlserver-kit.git
git remote -v
git remote add upstream https://github.com/ktaranov/sqlserver-kit
For actualizing your repo you could use simple command:
git fetch upstream
git checkout master
git merge upstream/master