Read through this first before opening GitHub-Lab.Rmd.
One person from each group should fork the repository.
That person then needs to add the rest of the group as collaborators.
Settings -> Collaborators -> Add collaborator
The group members will get an email which allows them to contribute to the repo.
The issues tracker is a good way to manage bugs and features that need to be removed or added. Check out this issue
Open and follow along with the GitHub-Lab.Rmd file, using the repo created for your group.