Design - Use the existing classes



In vB3 it was soo easy, to develop add-obs, because we were able to use the existing css classes (tborder, thead, alt1, alt2, tcat, etc.... )
Because i have no clue of css, it's really hard to make a nice "UI".
I have 2 add-ons, where the php part is nearly finished, but the whole designstuff is missing.

Is there a "easy way" to learn this stuff, or anybody have a "list" when to use which class? ( i know it's impossible to have a real list, but maybe somebody here have a small overview list?*g* )