change white to transparent for animation

[masterweb2003]

I have looked all over and I cannot find a way to make the backgound of my animation transparent. I don't have photoshop or anything to do it so, I only have imaging and paint I think lol. I tried downloading it but for some reason that didn't work out. I found a website that does it, ( http://www.mit.edu:8001/tweb/form.html ) but it didn't work well because mine is an animation. It really sucks thoguh because that was exactly what I wanted, but it didn't work right does anyone know how to change it or where to go to change it. The animation is on this page if it helps:

http://www.california.bravehost.com/a%20temp.html

for some reason the second butterfly doesnt move, cant figure out why.