The header file looks fine (except for 'definetypething'). The source file needs to be modified somewhat, though. Keep in mind that you're working with a different language now, one that uses a much older compilation system.
The following code should do the trick. For every function that you provide an implementation, you'll have to specify it's 'origin'. That is, to what class it belongs. If you wrote a class definition around it, you'd be defining that class again and that's not going to work.
// Source file: myclass.cpp#include "myclass.h"namespace MySpace{ void MyClass::MyMethod(something.. ) { //Logic and actual stuff }}
Note that, for static functions, you may as well use loose functions: unlike C#, C++ does not force you to use classes.