Can using the Form Designer be explained in readable, unabbreviated English in Documentation?
Using Jamroom
Strumelia is right. It is slow but steady knowledge.
I can give you a little idea of how to deal with some of the items on the style editor.
When dealing with actual design, keep two tabs open. One to your site and the other to the style editor. When you make a change, refresh your tab with the page to your actual site, and see what it does.
As for the functions, kind of trial and error. I have made mistakes (I just did a whopper myself), but I chalk that up to learning.