html help: ads on the side

Gretings!

Newbie here.
First, I'd like to thank the developers of the great SEO mod for their excellent work.

I want to serve ads both at the top, and at the right side, just like in this forum here, but I'm not good in html, and also I don't know what file to edit.
Is there somewhere any tutorial or post explaining how to do this please?

Many thanks in advance.