First of all, if you are starting from "hi i have no clue" i would recommend you build the website locally first, so you know the difference between remote and local, and all the thigns that make up the difference. You will need to pick an ide, if you want to write the language code from scratch, which is probably the easiest.
To build cat boucne, you just need some ready cat graphics, and a css file.
Every web page is an .html page, and thats for structure only. Design is from a css file. I recommend you get a sub to an ai like cluade grok or chatgpt, to help you. Once you have mastered and got it working lcoally, then you can ftp into a cloud server, and upload the files, you'll be lucky if you need 4-6 files at most even if you are highly organised. As soon as you host online, you have to start paying money, there really is no solution for hosting for free. Thats why i suggest offline first. Get it working 100 with an IDE like visual studio code, or jetbrains.
Edit!
I should say that a javascript file is for on page actions that css can't do.
