Problem
Need add event for any keys on keyboard.
Solution
We will use stage. And KeyboardEvent.Key_DOWN.
Detailed explanation
stage.addEventListener(KeyboardEvent.KEY_DOWN, ballAnimation);
function ballAnimation(e:KeyboardEvent):void
{
ball.nextFrame();
}
myBtn.addEventListener(MouseEvent.CLICK, ball2Animation);
function ball2Animation(e:MouseEvent):void
{
ball2.play();
}

Source:
keyboardEvent
