A big part of what's going on with the validation (not all by any means) is that it's being checked as HTML 4.01 Transitional, which it isn't. (Broadly speaking, it's mostly HTML 3.2, still with a lot of errors. HTML 3.2 wasn't really a standard, it was simply a description of what was being used around the time the document was created.) (BTW, the W3C validator has a lot of problems, and its results should always be taken with a grain of salt. Think of it as a spelling-and-grammar checker in a word processing program: it doesn't always know all of the words you're using, its grasp of real-world grammar is questionable, relying on some rules that aren't really rules, and it doesn't know local dialects (which you can read as "things needed to make the browsers and accessibility tools people actually use happy".))
It's pretty clear that you were using some very old reference materials; the dialect of HTML you're speaking stems from a very awkward period in history we'd rather not speak of anymore. (It's like the plaid polyester leisure suit era of computing. We're sorry. We thought it was the future. We thought we had to do that.) Into that, you've mixed a few bits of a much newer version of the language. That's going to cause some problems, since the browser won't be able to figure out exactly which set of rules to play the game by. For instance, you're using a <font> tag (which was deprecated long ago) to make a heading look like a heading without being semantically marked as a heading (not useful to the visually impaired), but you're also using ARIA attributes (new and not fully supported yet) to tell a screen reader which tone of voice to use on a link. Browsers are amazingly good at making some sort of basic sense out of just about anything you send them, but if you tell them the rules to use, then play by those rules, everything will work much better with many fewer surprises.
That said, there's nothing wrong with using Notepad to make a page (although it's harder than it needs to be), and there's nothing there that can't be fixed fairly easily. But you really need to get some more up-to-date reference material to help you along the way.
standards have changed. You need to be clear on your code. Else just use a CMS like WordPress to help you with getting a blog or website up. (that's another thing to learn).