Flash Action Script 3 is giving me 1120 error help please!

Question

I am having trouble coding this tutorial. I have changed it a little to fit my photos. I am getting this error 1120 below:
Scene 1, Layer 'actions', Frame 1, Line 1    1120: Access of undefined property btn1.
Scene 1, Layer 'actions', Frame 1, Line 2    1120: Access of undefined property btn2.
Scene 1, Layer 'actions', Frame 1, Line 3    1120: Access of undefined property btn3.
Scene 1, Layer 'actions', Frame 1, Line 4    1120: Access of undefined property btn4.
I don't really understand the coding and need help fixing this problem. I believe their code is wrong because my gallery will not work from the tutorial.
The code I have is below:
stop(); btn1.addEventListener(MouseEvent.CLICK,play1); function play1(event:MouseEvent):void{ gotoAndStop ("rosie") }
  btn2.addEventListener(MouseEvent.CLICK,play2); function play2(event:MouseEvent):void{ gotoAndStop ("mel") }
  btn3.addEventListener(MouseEvent.CLICK,play3); function play3(event:MouseEvent):void{ gotoAndStop ("liz") }
  btn4.addEventListener(MouseEvent.CLICK,play4); function play4(event:MouseEvent):void{ gotoAndStop("kayla") } ;
The code that was given to me is below: (Source:How to create a simple image gallery in flash cs5) :
  stop(); btn1.addEventListener(MouseEvent.CLICK,play1); function play1(event:MouseEvent):void{ gotoAndStop ("young") } btn2.addEventListener(MouseEvent.CLICK,play2); function play2(event:MouseEvent):void{ gotoAndStop ("thoughtful") } btn3.addEventListener(MouseEvent.CLICK,play3); function play3(event:MouseEvent):void{ gotoAndStop ("dancing") } btn4.addEventListener(MouseEvent.CLICK,play4); function play4(event:MouseEvent):void{ gotoAndStop ("old") }
Can anyone help me with this tutorial or coding! That would be great. Thanks!!

Answer 1

Flash CS3 works with events.
To handle clicks you have to capture the click event
To load a link you have navigateToURL:
http://livedocs.adobe.com/flex/2/langref/flash/net/package.html#navigateToURL()