To create a website using GitHub pages you need to create an index.html
file into any repository (No matter what name your repository is).
Then you need to publish your repository to be able to have your website.
Settings
tabbranch
, in your case master branch
Your repository will be online at http://username.github.io/yourRepoName
If your repository name is username.github.io
your website will be live at http://username.github.io
Also, you need to know that you can only public static websites.
Understand GitHub Pages reading this.