Intersection of two feature

Hi forum

I need your help.
I would like to create a function that calculates the intersection area of two features.
I use ArcMap 9.3.1, ArcObjects 9.3 and .NET language (particularly C#).
I would create a Tool Command that interset two Feauture of two different Personal Geodatabase (MDB).
I have no idea how to do it and I did not find code examples on the forum.
Could you suggest some code or some link, please?

Thanks in advance!