Buy a book on basic html, read tutorials and best of all practice what you leanr and make a portfolio site or just a test one and see what you can do and build on top of that as you learn new things. Thats how I learnt once you start doing that you wil pick it up real easy. Oh and XHTML is the way you want go.
html is very easy, just look up tutorials on the internet or get one of those for dummes books from your library and it'll walk u through it.
XHTML is after HTML 4.0 and is the transition b/w HTML and XML languages. XHTML is a better formed version of HTML, it closes tags properly, etc.
Tutorials/Trial and Error are the best way to go in my opinion. I was never taught(sp) anything about computers. Everything I learned was simply by playing around and reading up on my own. You'd be amazed how much you can learn that way. I'm not saying I have never asked someone to explain something to me but I've always worked on my own to learn something.