First of all, go to the Freespace tutorials, they will take you through the basics before you go on to more involved Web building.
Secondly, buy a good book to help you learn the really technical stuff - there are some recommendations in the Further reading section.
Thirdly - and this is more important than everything else, really think about what it is you want to do. I always say to people: what are your favourite sites, and why are they your favourites? Often, people find that it is a combination of how the site looks and how you actually use it and get around it. But, don't get too worried, everyone all over the world is still really on a learning curve even now, so join in and start building!