After you've decided what components your pages will be broken up into and created the sublayouts (renderings or server controls) each extending your base class, you can begin working on the setup inside Sitecore by configuring your component item's fields and setting up component insert options. These settings are stored on the sublayout items themselves and I'll detail them here.
The "Description" field is largely for you to provide a description of what the control does. I'm not aware of any place it is displayed but it's possible that it has other uses.
The "Parameter Templates" is one of