GitHub isn't a normal web host from which you can host a website. It is meant for versioning and sharing source code, including of web pages but of other languages too. Because of this, viewing a repository on GitHub defaults to showing the README.md file, which is what most other developers would want to know.
There are a few ways you can get GitHub to do what you're describing, i.e. serving raw files, including a service they offer called GitHub Pages but it's probably not as fully featured as what you're looking for. Instead, find a web host (just google it, there's thousands) and set up a cheap account. Shouldn't cost you more than a couple dozen USD a year.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…