How to create a behavior?

Can someone help me create behaviors for mobs and weapons? I have no idea how this behavior system works and I know that a lot of you guys know it... And you know it like a baws.
My Skype id is : valentin_games . ( the one with the name as a dot " . " )
Thanks in advance!

1. Not everyone here knows it
2. Behavior for weapons... never heard of that before
3. Will someone make a behavior for you for free? Most likely no

Didn't say that I want someone to make me a behavior. I meant to say that I want to learn how to make them.

How to learn:

Look at some behaviors already made in the source like Septavius