Im back in the shack

Well, can someone point me in the right direction about booleons. This is my aim:
A script to check you have an item. If true, you progress to another part to the dialouge. Im sure it has something to do with booleons. I mean, how would you go about doing that. And what type of booleons can you set for deifferent scenarios?
EDIT: Also, how do you go about using the goodbye function. Can you note an example on how this is used?