This creates an instance of a window. The window could be one of your own creation, or one of the built-in windows.

//create wnd of the 'class' just registered
hwnd = CreateWindowEx(0,                                  //more or 'extended' styles
                     chClassName,                        //the 'class' of window to create
                     TEXT("Rich Edit Controls"),         //the window title
                     WS_OVERLAPPEDWINDOW,                //window style: how it looks
                     GetSystemMetrics(SM_CXSCREEN)/4,    //window position: left
                     GetSystemMetrics(SM_CYSCREEN)/4,    //window position: top
                     GetSystemMetrics(SM_CXSCREEN)/2,	  //window width
                     GetSystemMetrics(SM_CYSCREEN)/2,	  //window height
                     NULL,                               //parent window handle
                     NULL,                               //handle to this windows's menu
                     hInstance,                          //application instance
                     NULL);                              //user defined information