Adding sound to flash game

Question

Hi
I'm making a simple game in flash and I need to add a sound effect when the character jumps (space bar) but I cant figure out what code I need to use. Can someone plz help me. Here is the code I have in the Player_Platform.as
package
    import flash.display.MovieClip;
    import flash.events.KeyboardEvent;
    import flash.ui.Keyboard;
    import flash.events.Event;
    public class Player_Platform extends MovieClip
        //Constants
        private const FRICTION:Number = 0.60;
        private const SPEED_LIMIT:int = 7;
        private const GRAVITY:Number = 0.8;
        private const ACCELERATION:Number = 1;
        private const BOUNCE:Number = -0.3;
        private const JUMP_FORCE:Number = -16;
        private const BOTTOM_OF_STAGE:uint = 10;
        //Variables:
        private var _vx:Number;
        private var _vy:Number;
        private var _accelerationX:Number;
        private var _accelerationY:Number;
        private var _frictionX:Number;
        private var _isOnGround:Boolean;
        private var _bounceX:Number;
        private var _bounceY:Number;
        private var _collisionArea:MovieClip;
        public function Player_Platform()
            _vx = 0;
            _vy = 0;
            _accelerationX = 0;
            _accelerationY = 0;
            _frictionX = FRICTION;
            _isOnGround = undefined;
            _bounceX = 0;
            _bounceY = 0;
            _collisionArea = this.body;
            this.ears.stop();
            //Add stage event listeners
            stage.addEventListener(KeyboardEvent.KEY_DOWN,atKeyDown);
            stage.addEventListener(KeyboardEvent.KEY_UP,atKeyUp);
            addEventListener(Event.ENTER_FRAME, onEnterFrame);
        private function atKeyDown(event:KeyboardEvent):void
            //Remove friction if the object is moving
            _frictionX = 1;
            if (event.keyCode == Keyboard.LEFT)
                _accelerationX = -ACCELERATION;
            if (event.keyCode == Keyboard.RIGHT)
                _accelerationX = ACCELERATION;
            if ((event.keyCode == Keyboard.UP)
            || (event.keyCode == Keyboard.SPACE))
                if (_isOnGround)
                    _accelerationY = JUMP_FORCE;
                    this.ears.play();
                    _isOnGround = false;
        private function atKeyUp(event:KeyboardEvent):void
            if ((event.keyCode == Keyboard.LEFT)
            || (event.keyCode == Keyboard.RIGHT))
                _accelerationX = 0;
                //Apply friction when the keys are no longer being pressed
                _frictionX = FRICTION;
            if ((event.keyCode == Keyboard.UP)
            || (event.keyCode == Keyboard.SPACE))
                _accelerationY = 0;
        private function onEnterFrame(event:Event):void
            //Initialize local variables
            var playerHalfWidth:uint = _collisionArea.width / 2;
            var playerHalfHeight:uint = _collisionArea.height / 2;
            //Apply Acceleration
            _vx += _accelerationX;
            if (_vx > SPEED_LIMIT)
                _vx = SPEED_LIMIT;
            if (_vx < -SPEED_LIMIT)
                _vx = -SPEED_LIMIT;
            _vy += _accelerationY;
            if (_vy > SPEED_LIMIT * 3)
                _vy = SPEED_LIMIT * 3;
            //No speed limit for jumping
            //Apply Friction
            if (_isOnGround)
                _vx *= _frictionX;
            if (Math.abs(_vx) < 0.1)
                _vx = 0;
            if (Math.abs(_vy) < 0.1)
                _vy = 0;
            //Apply Gravity
            _vy += GRAVITY;
            //Apply Bounce from collision with platforms
            x += bounceX;
            y += bounceY;
            //Move the player
            x += _vx;
            y += _vy;
            //Reset platform bounce values so that they
            //don't compound with the next collision
            _bounceX = 0;
            _bounceY = 0;
            //Prevent object from moving up if
            //it's not on the ground
            if (! _isOnGround)
                _accelerationY = 0;
            //Flap ears only when going up
            if (_vy >= 0)
                this.ears.gotoAndStop(1);
                _isOnGround = false;
                //_directionY = "down"
            //Stage boundaries
            if (x + playerHalfWidth > stage.stageWidth)
                _vx = 0;
                x=stage.stageWidth - playerHalfWidth;
            else if (x - playerHalfWidth < 0)
                _vx = 0;
                x = 0+playerHalfWidth;
            if (y - playerHalfHeight < 0)
                _vy = 0;
                y = 0 + playerHalfHeight;
            else if (y + playerHalfHeight > stage.stageHeight - BOTTOM_OF_STAGE)
                _vy *= BOUNCE;
                y = stage.stageHeight - playerHalfHeight - BOTTOM_OF_STAGE;
                _isOnGround = true;
        //Getters and Setters
        public function get isOnGround():Boolean
            return _isOnGround;
        public function set isOnGround(onGround:Boolean):void
            _isOnGround = onGround;
        public function set vx(vxValue:Number):void
            _vx = vxValue;
        public function get vx():Number
            return _vx;
        public function set vy(vyValue:Number):void
            _vy = vyValue;
        public function get vy():Number
            return _vy;
        public function get bounceX():Number
            return _bounceX;
        public function set bounceX(bounceXValue:Number):void
            _bounceX = bounceXValue;
        public function get bounceY():Number
            return _bounceY;
        public function set bounceY(bounceYValue:Number):void
            _bounceY = bounceYValue;
        public function get collisionArea():MovieClip
            return _collisionArea;

Answer 1

Thank you for your reply.
How can I convert it to an MP3 file?
Do I have to download software for that?