Fork a repository
If you want to commit/make a pull request to a repository, while you aren't a collaborator (no access rights on it), you need to fork it: create your own copy of the repository.
- go to the page of the repository
- click on the fork button 😆
Then you can either work on the project for yourself, or
- create a branch
- submit a pull request to the initial repository
You can read the official tutorial here.