About Scroll function of CWnd

I try to develop a control, whose basic class is CWnd.
The control is used in the Dialog. The function of it is somelike CScrollView (because it seems that CScrollView cannot be put in the Dialog as a control). So that I can draw (line,circle...)in that control without area limits.
But the problem is that I don't know how to do this (I know how to add scroll bar in CWnd).
So, the question is:
1. how to set the region of the Client Area of a CWnd anytime during the program. (such as the visible area is (100,100), the Client area I want to set it to (300,300).
2. how to show the clientarea when move the scroll bar. ( such as, the current client area is((0,0),(100,100)), if I moved the scrollbar to let it shoe ((100,100),(200,200)),how to convert it to the visible area, how to show it?)
If anybody know the theory or how to do that, please teach me ASAP. (if u can, samplecode will be prefered)
My email address: [email protected]
Thanks very much