When you create a new image, go into the advanced optotions and choose background --> transparency. The default is white.
And... The background image? Oh, sorry. I just had to use it, even though it was done by some poor crack-smokin' idjiit from Alabama... And it's ugly, too. <3
Uhhhhmmmm.... Your DS, all your games, a lightsabre, Cade Skywalker's brain, your laptop, a mouse, a monkey, a fluoro-pink nuclear warhead, Emma...
And NFSU2.