All you need for personal use is at http://www.w3c.org
But that is just the beginning. For commercial sites far more is required of web sites.
http://reviews.cnet.com/5208-6121-0.html?forumID=45&threadID=31673&messageID=361873 and its reply covers the rest.
How do I become proficient in webdesign on my own and what materials do I require?