Well written and with all the basics and more is NCSA's Beginner's Guide to HTML. Highly recommended. It also has more links in case you like a second opinion.
If your first language isn't english, you might try your luck with The Bare Bones Guide to HTML by Kevin Werbach, available in 10 languages!
Check out Yahoo's links on Web Authoring. They have links to everything from icons and backgrounds to hints and tips on making great homepages.
If you need to know the technical details, start with HTML 2.0 Authoring by Daniel Kew and follow up with HyperText Markup Language Specification 3.0 by Dave Raggett.
Microsoft's Cascading Style Sheets Gallery will learn you how not to use stylesheets.
Netscape's pages on Stylesheets, trying to get us using their "open standards".
The advanced HTML reference may actually give you a few ideas about how you should use stylesheets.