Transparent background badge, HOW?

okay, so i've been messing with the kill badges, but if i edit it, there's gonna be a white or w/e colour background to it, it losses it's transparent background. How do i make it transparent?

note: i've tried to save background as transparent, but Ps will just fill it in with white

the alpha channel, there's is black & white, black represents 100% transparent, white 100% visible, and gray is in between, when you edit your badge, you have to edit the alpha channel to match.