[Zope] Help on ZCatalog

Hi, I have created a ZClass and would like to use a ZCatalog, I have not been able to find any tutorial or an example to make this work. For example, I want to create a ZClass to contain CD objects, as in the tutorial. I now want to build a search screen to find all my Jimmy Buffett CD's. I use ZCatalog for that. I was able to set up a ZCatalog and find the CD instances, but that is as far as I could get, I don't understand how to search for ARTISTNAME = *, or something similar. Thanks, Willie