how to ADD reference in c++?

[spartan]

Hello
I have two pieces of codes. first is written in c++ as general program while second is the API of that code written in c#. How i can add dll of c# in c++ code?
Also there are two methods
1- Adding reference of dll in c++ managed code
2- Adding referencr of dll in c++ unmanged code
can any body please explain me the two methods or give me the link.
Thank in advance for your kind help.