How can I initial my function in AS3 - actionscript-3

Question

I am a beginner of AS3. I want to create a simple bouncing ball in a space limited in the canvas of 400*450. But it cannot work when I publish it. Anyone can help me figure this out?
PS: Is there any nice website can help me learn more things about AS3?
Here is my code:
function ballmoving(evt:Event = null):void
{
var vel_x = 5;
var vel_y = 6;
ball.x = -20;
ball.y = 280;
ball.x += vel_x;
ball.y += vel_y;
if (ball.x > stage.stageWidth - ball.width / 2 || ball.x < 0 + ball.width /2)
{
vel_x *= -1;
}
else if (ball.y > 280 || ball.y < 0 + ball.height /2)
{
vel_y *= -1;
}
}
ballmoving();
RecycleButton.addEventListener(MouseEvent.CLICK, reset);
function reset(event:MouseEvent):void
{
ball.x = -20;
ball.y = 280;
ballmoving();
}

Answer 1

Try something like :
var vel_x = 5;
var vel_y = 6;
function ballmoving(evt:Event = null):void
{
ball.x += vel_x;
ball.y += vel_y;
if (ball.x > stage.stageWidth - ball.width / 2 || ball.x < ball.width /2)
{
vel_x *= -1;
}
if (ball.y > 280 || ball.y < ball.height /2)
{
vel_y *= -1;
}
}
stage.addEventListener(Event.ENTER_FRAME, ballmoving);
RecycleButton.addEventListener(MouseEvent.CLICK, reset);
function reset(event:MouseEvent):void
{
ball.x = -20;
ball.y = 280;
}