How to i make a countdown timer for a game

How do you create a countdown timer on an animated game, so that when the time gets to 0 and depending on your score it ttakes you to a losing page or a winning page.

This is my code so far.

I want the timing to be 60 seconds and if the score is

stop();

var score:Number=0;

addEventListener(Event.ENTER_FRAME,testHit);
function testHit(e:Event){
if (kissBoy.hitTestObject(kissGirl)){
trace(“Hit”);
score+=5;
scoreDisplay.text=“score:”+score
}
}

function runalltime(evt:Event):void{
if (kissBoy.hitTestPoint(kissGirl.x,kissGirl.y,true)) {
kissGirl.x=Math.random()*400;
kissGirl.y=Math.random()*300;
}

}

function keydetect(evt:KeyboardEvent):void{
if(evt.keyCode==Keyboard.RIGHT){
kissBoy.x+=10;
}

if(evt.keyCode==Keyboard.LEFT){
kissBoy.x-=10;
}

if(evt.keyCode==Keyboard.UP){
kissBoy.y-=10;
}

if(evt.keyCode==Keyboard.DOWN){
kissBoy.y+=10;
}
}

stage.addEventListener(Event.ENTER_FRAME,runalltim e);
stage.addEventListener(KeyboardEvent.KEY_DOWN,keyd etect);

The other two frames are called gameWin and gameLose, so depending on the score within the 60 second countdown, how would i make it go to there frames and how would i make the time show up on the page.