#2 Dec 09, 2007 12:23
Rappybas what you seek has been covered many times. A plugin for this type of thing is possible, but given the vast number of potential advertisers out there and the internal structure of b2evolution, it makes so much more sense to edit your skin's _main.php file and add your ads directly.
Please. Search the forums for adding stuff to the sidebar (in general). I think a bit of diligence on your part will reward you with more than enough information to take care of what you seek.