I need serious help with classes

I’ve read quite a few Adobe Flash Lab documents talking about how to create custom classes. But I didn’t get what they were talking about at any stage because they use terminology related to classes that I don’t recognize.

What I am trying to do is make a class that will draw a quadrilateral shape according to some points but it refuses to work.

Can anyone change it in order to make it work plz?
also, does anyone have any links to a proper tutorial concerning classes?

Thanks