Using arrays to load mc's from library

Hi, i am a full beginner so this may seem stupid!!
basically i’m creating a little movie player. i have 3 buttons on stage that when clicked i want to load a movie clip from the library into my “container” MC already on stage. basically i want it so when i click on a button it changes the first and only array item to the one i want to load. therefore replacing the existing one. (so there is only one in the container at a time).
here is what i have . . .

var buttonOn1:button1 = new button1();
var buttonOn2:button2 = new button2();
var buttonOn3:button3 = new button3();
var container2:container = new container();
var rectangleOn1:rectangle = new rectangle();
var rectangleOn2:rectangle2 = new rectangle2();
var rectangleOn3:rectangle3 = new rectangle3();
addChild(buttonOn1);
addChild(buttonOn2);
addChild(buttonOn3);
addChild(container2);
buttonOn1.x = 0;
buttonOn2.x = 200;
buttonOn3.x = 400;
container2.y = 150;

var myArray:Array = [];
myArray[0] = rectangleOn1;
buttonOn1.addEventListener(MouseEvent.MOUSE_UP, buttonOn1Do);
function buttonOn1Do (event:MouseEvent):void {
myArray[0] = rectangleOn1;
container2.addChild(myArray);
}
buttonOn2.addEventListener(MouseEvent.MOUSE_UP, buttonOn1Do);
function buttonOn2Do (event:MouseEvent):void {
myArray[0] = rectangleOn2;
container2.addChild(myArray);
}
buttonOn3.addEventListener(MouseEvent.MOUSE_UP, buttonOn1Do);
function buttonOn3Do (event:MouseEvent):void {
myArray[0] = rectangleOn3;
container2.addChild(myArray);
}

by all means laugh at me if its overly complicated and im doing totally the wrong thing!

this doesnt work at all!!!

Andy