How to animate the movieclip using actionscript 3.0

Hello,

(Please see the attachment ‘sample.fla’
Flash CS4
Player 10
Actionscript 3.0)

Main timeline has only one layer ‘actions’.

There is a main movieclip named ‘shape’ (exported to actionscript with classname ‘Shape’ (linkage property)).

Inside shape there are two keyframes.
1st keyframe contains another movieclip square inside it.
Square movie clip has many frames (with different colored square)

Similarly 2nd keyframe has another movieclip circle.

When I press the right key the movieclip square at the first frame inside the shape movieclip should play and displace along x axis with speed say 10.

When I press the left key the movieclip circle at the second frame inside the shape movieclip should play and displace along -x axis with speed say 10.

But the problem is:

I press right key then the square moves right and when I release it stops.(works)

Then i press left key, then the circle should start from the position of the in the stage from where the square is present.(<- how to do this)

Similarly if I press right key the square should begin its movement from the position of the circle in the stage.(<- how to do)

(Initially we assign a starting location for the shape movie clip from where it begins.)
How to do that.
Please help me.
Thank You