I did it randomly before… here is what i had
function attachRandom() {
    goAway();
    var mcArray:Array = new Array("Animation1", "Animation2", "Animation3", "Animation4", "Animation5", "Animation6");
    var ranMc:Number =  Math.floor(Math.random() * mcArray.length);
    var mc:MovieClip = _root.middleStage.attachMovie(mcArray[ranMc], "Animation" + [ranMc], _root.middleStage.getNextHighestDepth());
}
this is attaching Animation1, Animation2, etc from the library to stage.
help please :stare: