Create DLL+Calling unmanaged dlls dynamically in C#.NET

Question

Hello,

I have found tutorial how to use some dll by importing it to the C# code, but nothere I can find information how to create such dll in Visual Studio. For example I have some Test.cpp file and I want to create a dll from it, what should I do first in Visual Studio? Please help me by some information, I am stuck here on this problem.

Thanks