Well, there are a galillion ways to place advertisements in your forum. What exactly are you looking for information about? Where to place them? How to? What script to use for management?
Here is a good start as to what locations seem to work best for CTR with adsense. Would imagine it's similar to any other ad being displayed there.
https://www.google.com/adsense/suppo...n&answer=43868
I would use openads if you have rotation and multiple positions, otherwise, you can start simple by hard coding them in the desired location, or use vBulletin's ad location templates.
Anything else?