Writing codes in MFC ActiveX Control

I am trying this article. The Hybrid Solution Part. I was wondering if you could help me out how do I begin writing those codes on Visual C++. I don't have background yet in Visual C++ MFC ActiveX Control and what I did so far is to create the Project. I also added a Dialog and a class but I get an error "Identifier IDD_DIALOG1 is undefined". I don't know if I am doing right. I don't know if adding a dialog is needed in this project because the author hasn't included what to do in MFC ActiveX Control so I am getting a hard time. Honestly, I don't understand the MFC ActiveX Contorl part that's why I don't know how to begin with so kindly help me. Thanks! :)