Slide show...please help

I am a new to scrippting, trying to learn, looked through dozens of tutorials…just can’t figure out how to do this : I need to create simple slide show where movie clips are rotating in loops in certain amount of time, one fades out while another fades in. I managed to do it with clicking on button. But I need to make it rotate automatically, without clicking on button .
I put each mc on separate layer and in first frame put:

[COLOR=“Navy”]var aImages:Array = new Array(mcOne, mcTwo, mcThree, mcFour);
var nCurrentIndex = 0;
var nInterval:Number;

nextButton.onRelease = function():Void {
nInterval = setInterval (fadeImage, 50, aImages [nCurrentIndex]);


function fadeImage (mcImage:MovieClip):Void{
mcImage._alpha -=12;

if(mcImage._alpha <= 0) {
	clearInterval (nInterval);


But how can I make it work without pressing on button?