How do I alter certain elements of a style?

[s0lidgr0und]

I just skimmed through the articles and did a few searches of the entire forum, but I didn't see exactly what I was looking for. Basically I was looking for some sort of tutorial/article/chart that would show me which css characteristic corresponded with certain parts of a given style. I know I saw a jpg file on another forum that was posted from here that went so far as to have a screen capture of a forum page with text and arrows illustrating which files had to be altered to change the certain parts of the board.

For instance, is there a place I can change the entire board's default font to be Tahoma? Is there a way I can edit the box-like appearance of some of the borders and maybe replace them with softer edges that I could customize myself? I'm okay with the default blue style that vBulletin comes with, I'd just like to do a few of these slight alterations to make it a little more like I want it.

Thanks for any input.