Please see the README on the main repository
Also, please consult the wiki on the main repository.
The purpose of this repository is to store the educational code which is separate from the production code for the main robot. This is a great place for new members to start working on things--some of which may be able to be integrated into the main repository at a later date.
First, install git for your machine. Git is available at https://git-scm.com/, and it works on Windows/Mac/Linux/et al.
For Windows and Mac, there is a Github client that you may want. It is available at https://desktop.github.com/. For Windows, I can recommend TortoiseGit which may be downloaded at https://tortoisegit.org/.
There is a short git tutorial that I recommend at http://rogerdudler.github.io/git-guide/