Ok, are you using an edit control or are you drawing the text on the window yourself?
If you're using an edit control it should supply it's own scroll bars when you use the WS_VSCROLL and WS_HSCROLL styles.
If you are drawing the text yourself, then you need to process the WM_VSCROLL and WM_HSCROLL messages yourself... that is, you have to redraw the text according to the scroll bar positions.
It might help if you could post the relevant parts of your code...