This guy released a book, but his website http://www.designmeltdown.com is larger and more complete (and useful) than the book will ever be. Other than that learning the coding and basic principles of design would be the main focus. Even if you use a WYSIWYG editor, having a working knowledge of HTML, XML, Actionscript and some other languages can be very useful.
Look for books by influential web design people who also have blogs. These are people like Jeffrey Zeldman, Eric Meyer, Dan Cederholm, and so on. And if you read their blogs enough, you'll be able to find other influential web people and their books.
Cap'n Nick (post: 1315617) wrote:This site is really cool, mechana! I'll definitely be spending some time here.
That... is pretty much what happened when I found out about it. I've been reading through the whole site in preparation for building my own portfolio site.