Some Problems with my AS3 code - actionscript-3

Question

Some troubles to make my new flash game(i used AS3,CS5.5):
I just try to make my character(hatt) walk and jump, but I can't make it at the same time, well, idk how... Furthermore, I don't know how make my character recognize the ground.
And at last this thing here:
"Scene 1, Layer 'hatt', Frame 1, Line 6 Warning: 1090: Migration issue: The onKeyDown event handler is not triggered automatically by Flash Player at run time in ActionScript 3.0. You must first register this handler for the event using addEventListener ( 'keyDown', callback_handler)."
Plz help me and give some hints plz... Thanks.
Here's the code:
var grav:Number = 10;
var jumping:Boolean = false;
var jumpPow:Number = 0;
stage.addEventListener(KeyboardEvent.KEY_DOWN, onKeyDown);
stage.addEventListener(Event.ENTER_FRAME, update);
function onKeyDown(evt:KeyboardEvent):void
{
if (evt.keyCode == Keyboard.UP)
{
if (jumping != true)
{
jumpPow = -25;
jumping = true;
}
}
}
function update(evt:Event):void
{
if (jumping)
{
hatt.y += jumpPow;
jumpPow += grav;
if (hatt.y >= stage.stageHeight)
{
jumping = false;
hatt.y = stage.stageHeight;
}
}
}
stage.addEventListener (KeyboardEvent.KEY_DOWN, myFunction) ;
function myFunction (event: KeyboardEvent){
if(event.keyCode == Keyboard.LEFT) {
hatt.x -= 5
}
if(event.keyCode == Keyboard.RIGHT) {
hatt.x += 5
}
}

Answer 1

remove this line:
stage.addEventListener(KeyboardEvent.KEY_DOWN, onKeyDown);
remove function onKeyDown:
function onKeyDown(evt:KeyboardEvent):void
{
if (evt.keyCode == Keyboard.UP)
{
if (jumping != true)
{
jumpPow = -25;
jumping = true;
}
}
}
replace myFunction with this:
function myFunction (event: KeyboardEvent)
{
if(event.keyCode == Keyboard.LEFT)
hatt.x -= 5;
if(event.keyCode == Keyboard.RIGHT)
hatt.x += 5;
if(event.keyCode == Keyboard.UP && jumping != true)
{
jumpPow = -25;
jumping = true;
}
}