To be able to create a pull request, is required to have an account on Github, to do so, go ahead to it's sign up page, and follow the steps.
1.- Enter your basic information
2.- Check that you're not a robot 🤖.
3.- Press the "Sign Up" button.
4.- Setup the basic settings.
5.- Check out your email, then click on the link that you've received on it to validate your account.
6.- ¡Congratulations, you have a Github account! 🎉