Random bg fade

I want to load an random background image:

This is what I fond on the forum:


images = ["1.swf", "2.swf", "3.swf"];
randomNr = Math.round(Math.random(images.length-1)*10)
container.loadMovie(images[randomNr]);

but :thumb:

i need to fade out the bg after 20 seconds and fade in another random background image

help me :flower: