that is about receiving events but he wants to "send" (emulate) the event.
The Windows SDK tells you how (user32.dll API):
SendInput Function () Code:
void LeftClick ( )
{
INPUT Input={0};
// left down
Input.type = INPUT_MOUSE;
Input.mi.dwFlags = MOUSEEVENTF_LEFTDOWN;
::SendInput(1,&Input,sizeof(INPUT));
// left up
::ZeroMemory(&Input,sizeof(INPUT));
Input.type = INPUT_MOUSE;
Input.mi.dwFlags = MOUSEEVENTF_LEFTUP;
::SendInput(1,&Input,sizeof(INPUT));
}