MESSAGES, HANDLERS and OBJECTS are the building blocks of scripts; FUNCTIONS, PROPERTIES and COMMANDS carry out the work of the scripts. You can find lists of these in a good HyperTalk manual; you don't need to memorize them all -- look them up when you need them.
We have tried to make our scripts self-explanatory. For an understanding of how we wrote OPEN STACK, go to the circulation card and look at the scripts for the stack and the background (you know how to get to scripts now, right?). We can't guarantee you'll understand what we're babbling about, but we bet you'll learn a lot trying.