COM implementation

I am trying to implement ODMA standard in my application. I have got the API specifications. However I do not know how to go about implementing those interfaces. My application will basically be interfacing through a function called ODMGetODMInterface and through three COM interfaces; IODMDocMan , IODMQuery and IODMDocMan2. I would like to implement it in VB. Therefore should I declare 3 classes IODMDocMan , IODMQuery and IODMDocMan2 and the function ODMGetODMInterface in a bas file.
I can't get to know where and how to start with it.
Besides the syntax of the function is
HRESULT ODMGetODMInterface( REFIID riid, LPVOID FAR *ppvObj, LPUNKNOWN pUnkOuter, LPVOID pReserved, LPSTR lpszAppId, DWORD dwEnvData )
which is in VC++ how do I get it in VB. Please help someone.