Start by learning HTML, which is pretty easy. Then learn CSS to contol how things look. A couple of books to consider:
Designing with Web Standards by Jeffrey Zeldman
The Zen of CSS Design by Dave Shea
Neither of these is a technical manual, rather lead by example.
Sites that are useful:
csszengarden.com
stylegala.com
alistapart.com
Valid XHTML/CSS is a bit more difficult to learn to start with compared with layout in something like Dreamweaver, but the rewards are worth the extra work.