How do you import definitions from a C library using mono and Runtime.Interopservices?

Question

I am totally unfamiliar with C-Sharp so this is all new to me but I have a framework I am trying to use with mono.

I can import functions from the framework fine, but there are a lot of for instance type definitions (in the form of C preprocessor directives not that I imagine that should make any difference) and definitions of all the error codes.

Now one thought is to just include the header files in the project, but am I right in thinking there is a way to just import them from the framework directly and how do you go about doing so?

As an aside I am working on Mac OS 10.9.1 using Xamarin Studio so any Visual Studio specific solutions will be ineffective.