Here is a solution using code snippets
Code:
import flash.events.TimerEvent;
var fl_TimerInstance:Timer = new Timer(1000, 10);
fl_TimerInstance.addEventListener(TimerEvent.TIMER, fl_TimerHandler);
fl_TimerInstance.addEventListener(TimerEvent.TIMER_COMPLETE, TimesUp);
fl_TimerInstance.start();
var fl_SecondsElapsed:Number = 10;
Countdown.text =String(fl_SecondsElapsed);
function fl_TimerHandler(event:TimerEvent):void
{ fl_SecondsElapsed--;
trace("Seconds elapsed: " + fl_SecondsElapsed);
Countdown.text =String(fl_SecondsElapsed);
}
function TimesUp(e:TimerEvent){
trace("Times Up!~")
}