ActionScript 3.0 :: Circles That Act As Mask For Picture

I've got the code for circle on an image (mask). I've got it in my first frame and I need do something else in 2nd frame but after the movie in 1st frame is finished.
Code:
//This container contains all the circles that act as a mask for the picture
var container:Sprite = new Sprite();
//Assign the container to be the image's mask
picture.mask = container;
//Add the container to the stage
addChild (container);
/*

This timer is responsible for creating a circle every 0.05 seconds. A total of 20 circles will be created.
*/
var timer = new Timer(50,20);
timer.addEventListener (TimerEvent.TIMER, createMaskBall);
timer.start ();
//The timer calls this function every 0.05 seconds
function createMaskBall (e:Event):void {
[Code] .....