If you are working on a public repositories in which you are NOT a collaborator, first fork the project using the "fork" button.
- Clone your project to your local machine.
- Make a new branch.
- Make your changes in the new branch.
- Commit your changes.
- Push your changes up to your repository.
- Click the "Compare & pull request" button.
- Click "Create pull request" to open a new pull request.