Lines to draw in a scroll bar

Please see the attached fla.
I am drawing several lines which progresses in horizontal direction.
I want that as the number of lines increases a scrollbar should come into the picture so that the lines which are getting lost when the movie clip size finishes can be seen in this scroll bar.

PS: I know that I have to place the movie clip in the scroll pane and set the horizontal scroll to be auto, but I am not sure how to do that so please explain clearly