This will help you find out which template(s) are begin outputted on a page and where their output starts and ends:
http://www.vbulletintemplates.com/mo...?threadid=1687
Editing the templates of vBulletin is quiet easy, they are listed in alphabetical order in the admin cp and common templates are gourped.
Inside of the templates you can use
replacements, these are very helpful as they allow you to keep colors and other things from begin hard coded in the html.