You would need to find the window with:
LPCTSTR lpClassName, // pointer to class name
LPCTSTR lpWindowName // pointer to window name
Which case you would receive a handle to the window.
Then you can send a message to that window with:
HWND hWnd, // handle of destination window
UINT Msg, // message to send
WPARAM wParam, // first message parameter
LPARAM lParam // second message parameter
When it came down to it I dropped everything and ran.
-Ramza Final Fantasy Tactics