I have not done custom themes for a forum - but i have for Coppermine photo galleries, and I would have thought tasks were similar.
Basically, producing any page as a photo-shop theme is usually a big no-no. Individual users will tweak their browsers to suit themselves, others will have accessibility requirements. And making the page search-engine friendly would be a nightmare, IMO. If you are, none the less, hell-bent on using your photo-shop layout, then you can either use a table, or, better, use CSS with absolute positioning.
I should think the v bulletin documentation will help you with how to introduce your own theme or skin. And I would hope it has its own support forum, which will be best-placed to give you further advice..
 The above comment was written before this thread was moved from the HTML section to this - which I must admit I didn't know existed. Oops. [/edit]
Last edited by kiwibrit; 11-28-2006 at 06:16 PM.
Reason: Movement of this thread from the HTML section.
The changeable elements in vbulletin are done with CSS in the styles. Click styles, then click the name of the particular style you wish to edit. To begin with there'll probably be just one, unless you create a new one.