So there are two main files you need. An .html file, and a .css file. .css is basically the visual aspects (basically making it more aesthetic), while html is the ''bones'' of your webpage. I'll likely jump around between the two so I'll try to label what I'm doing. Right now my html looks like this:
<!DOCTYPE html>
<html>
<head>
</head>
<body>
<h1> WELCOME </h1>
</body>
</html>
I don't know if I'll be covering what each term/tag means, so I do suggest using W3Schools or something else you find on Google. And perhaps this may be a controversial take, but you can also ask ChatGPT as well on definitions. I'm planning on using it to help me build this site. Not with the intention of prompting and copying whatever it spits out, but for to understand what am I really doing and why things work this way, and don't work otherwise, etc. I have found it useful to explain definitions to me whenever resources make it too simple or too complicated for me to understand.
I'm also going to look at the code of other people's sites on Neocities and see how they commonly format things so I can try to learn from them too.
Also, I learned to upload the code like the one above by using the pre and code tags. These sites helped explain it well:
Meyer Web's tutorial
Mozilla's documentation