There is no description of the stylesheet that I know of, but it’s fairly straightforward. Working on this should be identical to styling WP, only with different classes and ids. There is also no listing of template tags and other API functions, sorry.
Not sure what you want to do with the images, but some things can be done with CSS.
.post img {
property: details;
}
You can set things such as the border and the maximum size and the like. http://www.w3schools.com/css/
For incredibly fancy things with images you need swfIR, but that’s a flash thing and as such a) very annoying b) security risks? c) setup difficult.
Right now, by the way, you appear to be using Trent’s forum theme, which includes a (hardcoded?) link to his about page (second blue tab at the top).
You may also wish to re-count your forum’s posts (Admin > Site Management I think), as one of your forums has -1 posts.
