First, go to the top right hand corner (below the banner) of the member's home and edit your account. I think the last option is the one that says to downgrade to HTML mode, which is how you do it.
The most commonly used layout is the one at Eonlight Valley (http://eonlightvalley.com/), which is pretty basic. Then, you can read around and try to learn some basic HTML. To start, all you really need to know is:
* Image tags to put pics on your site <img src=>
* URL tags <a href="">text</a>
* Background images/color codes for the tables (it's in the style)
* Your basic <p align=(center, right, left) Blah Blah </p>
* Line breaks <br>
Then, you can learn the fancy stuff as you go. Don't go into HTML mode until you can handle it, though. Oh, and if any of the HTML above is wrong, anyone can correct me. I'm a bit rusty...-has been cheating with Front Page-
Also, there are some HTML resources linked to in the resource sticky.