People ask about accessing DLLs all the time and now there's a clear little tutorial on The Code Project on just that subject:
Regular DLL Tutor For Beginners
This tutorial is in five parts. It gives a step by step procedure for developing a Win32 DLL and a regular MFC DLL object. There are three client applications, two Win32 console applications (one for Load Time linkage and the other illustrates Run Time linkage), the third DLL client application uses the shared MFC Library.