NULL                        //menu handle or child identifier
hInstance                  // handle to application instance
NULL                        // window creation data
);
// if the function succeeds ,the return value is handle to the naw window
if(hwnd = NULL)
{
Message Box(NULL, "window creation Failed!" ,"Error!",
MB_ICONEXCLAMETION ! MB_OK);
return(0);
}
Show Window (hwnd ,iCmdShow);           //sets the specified windows show state.
second parameter can be SW_HIDE , SW_RESTORE
UPdate Window (hwnd);      // updates the client area of the specified window by sending a WM_PAINT message to the window.
while (GetMessage (& msg ,NULL,0,0)>0)
//   retrives the message from the calling thread's message queue
//   (message information ,handle to window , first message,last message)
//  handle to window = NULL means it retrives message for any window that belongs to the calling thread
{
TranslateMessage (&msg);    // translates Virtual-key massage into character message.