How do i load different content pages within scroller...?

hi all!
i have a scroller that consists of script, a mask (movie clip, instance name of text) and buttons.
in the mask is my mask and the page contents (also a movie clip with instance name of contents).

when an invisable button is released i want new text to appear in the scroller for the viewer to read.

can someone please explain how i can do this???
thanks so much!