Experts only!!!!

(1). What is GetWindow(); and how do I use it?
(2). How to get the object on another HWND(window)? How to declare the object?

Amplified:

(2). GetDlgItem(Hwnd2,EDIT2);
{ Hwnd2 is another window, not under my control, I didn't create it, how do I get EDIT2 on Hwnd2? Everytime I try to use this command it returns an error: "EDIT2 not Defined". and if I defined it, still I cannot get the control EDIT2. }
{ I used FindWindow() to obtained Hwnd2 and I know there's an object on Hwnd2 called EDIT2 }

1. GetWindow is used to explore the window tree, check out msdn for syntax
2. win32api is not object oriented, so all the handles represent the objects, you use the associated functions to create, modify and remove the objects. To retrieve a window that you don't have the handle (for instance for an external application) you use findwindow, enumwindows or getwindow

I dont understand, what is the poll for?? Your title is quite irrelevant if I may say so.