Noobie Question - pleae help?

Hello. Very new to flash. Gone through very basic tutorials. Someone gave me this file yesterday (see attached). Trying to duplicate this from the beginning but am having some problems. I see that the animation is made up from 4 shape tweens. How do you bend the edges of the square??
When I try to use the transform tool it doesn’t allow me to bend, just scale and skew. Any help or pointers would be appreciated.