[Zope] ZClass Selection Property and Catalog Aware questions

Hi, I have two simple (maybe stupid) questions: 1)I created a catalog-aware ZClass but its instances don`t catalog their content automatically as they are constructed. Did I miss something basic? 2)This class has a Selection property. If I understood correctly, I am supposed to write a DTML method to fill the selection. I did this in the "Methods" tab of my ZClass, but it doesn`t work... What am I missing??? Regards, Rogerio