How to add next back buttons to Image viewer (built w/ arrays)

1

I have to add one back button and one next button to my image viewer (built with arrays). what script should I apply to these buttons? what line of script should i add to my main code. Please help.

this.onLoad = function(){
mypictures = [“tibet.jpg”, “tibet2.jpg”, “forest.jpg”, “einstein.jpg”, “bear.jpg”, “dragon.jpg”, “af1.jpg”, “ceppu.jpg”]
numPics = mypictures.length;
randomNum = Math.random(numPics);
trace(randomNum);
randomNum = randomNum * numPics;
trace(randomNum);
randomNum = int(randomNum);
trace(randomNum);
thisTime = mypictures[randomNum];
trace(thisTime);
this.createEmptyMovieClip(“imageHolder_mc”, 1);
imageHolder_mc.loadMovie(thisTime);
this.imageHolder_mc._xscale = 60;
this.imageHolder_mc._yscale = 60;
this._x = 50; this._y = 40;
_root.photo_name.text = thisTime;

}

stop();