Creating ActiveX DLL

Hi All,
I am trying to create an ActiveX Dll based on another class that I have developed. Although I use Implements clause to get the Inheritance Feature but what my question is can I add any additional Properties or Methods to the one I am creating now. If so can any one inform me how to do this, 'coz I tried to implement this and though it compiled and generated the DLL properly without any error but I can't see the newly created Property/Method from my Test Project. Any help in this matter willbbe greatly appreciated.