Please help... next previous button question

1

Currently I have a single movie clip and next/ previous buttons attached to this movie clip. The image changes every 9 frames. Currently I have the code set to change at every frame. How do I get it so it changes at every 9 frames???

started flash just month ago… so please be gentle!

play();

previous_btn.addEventListener(MouseEvent.CLICK, goBackward);
next_btn.addEventListener(MouseEvent.CLICK, goForward);

function goForward(e:MouseEvent){
if(currentFrame == this.totalFrames){
gotoAndPlay(1);
}
else{
nextFrame();
}

}

function goBackward(e:MouseEvent){
if(this.totalFrames == currentFrame){
gotoAndPlay(this.totalFrames == 1);
}
else{
prevFrame();
}
}