Use multiple SWF's?


I am still trying to understand how this would work.

I am creating a flash with 2 boxes, one on top of eachother.
The top box will have an animation. The bottom box will have a scroll of thumbs (i can ge that working now - i think) but when the user clicks on a thumb it will launch a different animation in the top box.

What would be the best way to set this up? gotolearn has an example of the thumb scroller which only takes up 1 frame on the time line. If i add another layer and put the animation in that which will be about 100 frames then how will that work…? it would only play the first frame wouldnt it? and how would i set it to go to whichever animaiton without using gotoandplay(frame)? thats how i have been doing things so far and my timelines are geting bloody huge!!