Coding a tween

//Tween an object's _y property. This is within the context of a v2 Component, but the same principles also apply elsewhere. Just replace 'this' with the movie clip you want to tween.
 
import mx.transitions.Tween;
import mx.transitions.easing.*;
 
 
var tween = new Tween(this, "_y", Elastic.easeOut, y, yToMoveTo, 1, true);
tween.onMotionFinished = mx.utils.Delegate.create(this, motionFinished);