Click on + button in menu and then click on new repository.
Click on uploading an existing file.
Choose files to upload. (index.html, styles.css, script.js)
Click the Commit button.
Next you'll be redirected to your Repository.
Click on Settings.
Scroll down until you see Github Pages.
Click on the dropdown None and select master
branch.
Next click Save.
Now you can click on the url in the Github Pages settings section.