Flash ActionScript3 -- add snow falling

The steps to produce following animation (adding snow falling in Christmas card):
1) Click Adobe Flash CS3 Professional:
2) File->New ->ActionScript 3
3)  Rename “layer 1″ to “card”. On this layer import the image of your choice, you can take one www.xmas-wallpapers.com
4)Create a new blank keyframe, draw the shape of your snowflake and convert it to a movie clip. In property, select export for actionscript, export for first time.
Name Snowflake, class Snowflake, Base class: flash.display.MovieClip  Remove the snowflake keyframe from the stage, which is already in the library.
5). Create a new “actions” layer. Press F9 to import following actionscript

addEventListener(Event.ENTER_FRAME, createSnow);

function createSnow(event:Event):void{
    var snowflake : Snowflake = new Snowflake();
    snowflake.x = Math.random() * stage.stageWidth;
    snowflake.y = 0 ;
    addChild(snowflake);
    snowflake.addEventListener(Event.ENTER_FRAME, moveSnowflake);
}

function moveSnowflake(e:Event):void{
    if(e.target.y < stage.stageHeight){
        e.target.y += 10 + Math.random() * 5 ;
        e.target.alpha -= 0.015;
        e.target.scaleX = e.target.scaleY -= 0.01;
       
    }
    else{   
        e.target.removeEventListener(Event.ENTER_FRAME,moveSnowflake);
        removeChild(e.target as Snowflake);
    }
}
6) Control + Test Movie (ctrl+enter) to test movie. Export movie to swf file.