If you ever need to host or upload a very basic site containing html, css, js, txt, etc online; you should use https://htmlsave.com
We have a beginner friendly website, where we help you host and maintain a basic static site for your mockups.
Watch this video to get started:
After pasting the HTML code on the home page, you can create CSS, JS separately. Then you can paste the codes and submit to save it with Htmlsave.
It is really simple to start.