Basically:
- Create a github account.
- Download the github client:
https://windows.github.com/
- Tell me your account so i can add you as main contributor
- Download the repository from the github client
Then, you can:
- "Pull" to grab the latest modifications
- "Push" to send your modifications to the server
You can easily see what have changed, merge modifications if other people have changed the same as you. You can also modify directly from the site. This is the best to develop ! (edit: here is the workflow:
https://guides.github.com/introduction/flow/)
Try this:
https://try.github.io/levels/1/challenges/1
You will learn the basic commands which you don't really need with the client, but you will learn the concepts !