The header file contains definitions and declarations required by the C-language source file which are incorporated into the source code by an #include directive. Name the file GENERIC.H and make sure it looks like this:
#define IDM_ABOUT 100
int PASCAL WinMain (HANDLE, HANDLE, LPSTR, int);
BOOL InitApplication (HANDLE);
BOOL InitInstance (HANDLE, int);
long FAR PASCAL MainWndProc (HWND, unsigned, WORD, LONG);
BOOL FAR PASCAL About (HWND, unsigned, WORD, LONG);