You can create a branch off of a repository's default branch so you can safely experiment with changes.
GitHub Desktop tracks all changes to all files as you edit them. You can decide how to group the changes to create meaningful commits.
You can temporarily save your changes without committing them to a branch by stashing the changes.
You can see details about any commit in GitHub Desktop, including a diff of the changes the commit introduced.
As you commit changes to your project locally, you can push those changes to GitHub so that others may access them from the remote repository.
All GitHub docs are open source. See something that's wrong or unclear? Submit a pull request.
Or, learn how to contribute.