git clone https://github.com/ACPartners/TimeRegistrationDemo.git
Go to Team Explorer => Connections => Local Git Repositories => Clone and fill in our adress: https://github.com/ACPartners/TimeRegistrationDemo.git
Commiting you can do in Visual Studio or from the commandline
Sending code back to our repositories: When working with many people you don't just check in on the master branch, usually you make your changes on your own branch and make a pull request for this to be merged into master.