Image Fader

How can i do an image fader with out java or flash. (It has to work in NS). w3school has some good image faders but they only work in IE

Do you want the image to just fade in/out?
http://www.javascript-fx.com/navigation/imagefader/demo5.html
(works in IE4+ and NS6+)

Do you want Fading Image Rollovers?
http://www.javascript-fx.com/submitscripts/fading_rollovers/index.html

Or do you want fading in all browsers.
http://www.javascript-fx.com/gng/demo/picfader/

thanks.... I do know that site and now i ahve been tring to figur out how there fader works. But i simply cant. there fore i am asking if some one can explain it to me. PLEASE