First, follow this guide.
Then, create a iframe in your pages html that links to the repo you hosted on github.
<iframe src="https://[YOUR USERNAME].github.io/[YOUR REPO NAME]/" style="border:0px #000000 none;" name="Game name" scrolling="no" frameborder="1" marginheight="20px" marginwidth="px" height=850 width=100% position=absolute></iframe>
Width and height can be adjusted to your specifications. Pretty sure there is a way to host the file locally on your page itself if you are a supporter, but I haven't found a way to do that directly yet. Hope this helps!