render help

so im trying to make a signature and when i take the renders and pujt them in mircoworlds ex they always have a black ground and when i use the paint can white it takes they pads among other things and is annoying. does anyone have a way to fix that?
i need that of:
Miz, Bryan, Ryder, Rhodes, CM Punk, Christian, Roode, Aires, Jeff Hardy Laurnitausand aj styles