More Help with my button

Ok so basically I need to know what needs to be replaced with my button’s name (play) so that this script will go to the next frame when it is pressed:

 my_btn.addEventListener(MouseEvent.CLICK, onClick); 
 function onClick(event:MouseEvent):void {  
 this.nextFrame();  
 } 

And also I put in:

  Stop();  

at the beginning of my flash and it still keeps going through all the frames of my game even though that is supposed to stop it. what am I doing wrong Help greatly appreciated!