I'm not super good at using github (or git) but the general overview of the process is:
1. clone the repo.
2. setup your repo as a remote (labelled upstream)
3. check out a new branch
4. make your edits, and commit them.
5. push the branch to github
6. switch to your branch.
(note this is written from the point of view of using git at command line which is what I do using gitbash on windows)