I originally may have read into this wrongly, but if I was correct the first time, then this is what I would have said:
I would also recomend just googling whatever you need every time you need it. Sometimes more than once. Eventually you will know how to do anything you want in HTML. W3Schools and MDN Web Docs are great tools in this case, though make sure you take what they say with a grain of salt.
Also, if you are new to programming as a whole, then I would reccommend learning how to do that first.
However, in the case you know HTML/CSS/JS but you don’t know what is allowed on this site, you can basically do anything. They don’t care if you cheese the system either. How to start a new project: Start a New Project...How?