We use the pull-request model, see GitHub's help on pull-request.
In brief, you will:
- add an issue about what you plan to change;
- on GitHub, find and fork the source repository;
- on your computer, clone your fork repository,
- commit your changes in a new branch;
- push your branch and submit a pull-request for it;
- go through the review process until your pull-request is merged; and close your issue.
You can email us to 99xt@googlegroups.com if you have something to discuss further.