If you are not the maintainer for a project, but still want to contribute, you can clone the repo and modify files. You might fix a bug or add a feature. Then you can email a “patch” file containing your changes to the actual maintainer of the project. You might try to work on a specific bug or feature ticket.

git format-patch master --stdout > your-patch-file.diff

First create a new branch:

git checkout -b new-branch-name

Then apply the patch:

git am < their-patch-file.diff