The header file contains definitions and declarations required by the C-language source file that are incorporated into the source code by an #include directive. Name the file GENERIC.H. It should look like this:
#define IDM_ABOUT 100
int PASCAL WinMain(HINSTANCE, HINSTANCE, LPSTR, int);
BOOL InitApplication(HINSTANCE);
BOOL InitInstance(HINSTANCE, int);
LRESULT FAR PASCAL MainWndProc(HWND, UINT, WPARAM, LPARAM);
BOOL FAR PASCAL About(HWND, WORD, WPARAM, LPARAM);