how to compile C function in C-Sharp program?

Hi,

I do not know how to code in C Sharp. I want to add a C function to an existing, working C Sharp program, and compile it. Let's say the C function is something like this:

Test_Function ( )

{

/* C codes go here. */

}

What do I need to do to make this C Sharp program compile with the above test C function added? I tried adding standard C libraries at the top of the C Sharp program, but it won't compile.

#include "stdio.h"
#include "stdlib.h"
#include "string.h"

Please help. Thank you.