I Need A Help..Plz

I have Developed a action script for placing circles inside the flash.

Using this Code

init();
function init()
{
x = 10;
count = x;
top = 20;
left = 20;
bottom = 20;
right = 20;
balls = new Array();
for (var i = 0; i < count; i++)
{
var ball = attachMovie(“ball”, “ball” + i, i);
ball._x = Math.random() * Stage.width;
ball._y = Math.random() * Stage.height;
ball.vx = Math.random() * 2 - 1;
ball.vy = Math.random() * 2 - 1;
balls.push(ball);
}
}

The Animation Looks like the Following…

I want the animation to be occur inside the box…

Note: Don’t Confuse with box.The Box drawn by me After screenshot…

Plz anybody Give Solution for this.

And also i want another help following this thread…I post later…

If i make any mistake plz apology me…

With Helpless…
Gnanavel N