darwin_nacional 0 Newbie Poster

Hi guys, I'm trying to add a splash screen on my app but I can't seem to follow the instructions here in:

http://download.oracle.com/javase/tutorial/uiswing/misc/splashscreen.html ... creen.html

I'm using netbeans and I can't understand where to put the gif file. I have also tried editing the manifest.mf but I can't make it work.
Could someone help me out by giving me step by step instruction? The code and gif that I'm working with is the same as the one provided in the link. All the tutorials on the net says the same thing and I can't find any good tutorial on youtube.