In order to create a GitHub page, you must create a new repository:
After creating a repository, publish or push files that you need. Then on your repository, click add README:
After modifying your README file, go to settings:
On the GitHub Pages, you’ll see Source option and pick the repository that you want to include on your page.
Click on Save and under the Source, there is a Theme Chooser where you can freely choose the them for your GitHub page.
You can see that there is a link above the Source, click on that link and you’ll see your GitHub Page.
It usually take up 10- 20 minutes to generate your site. Be patient.