Hi!

I have created a 100 frame animated scene in Maya and then I made a a Software Render on that (so I have 100 images on that render), and then I created a Hardware Render on the particles (sparks from a fire(100 frames)).

I know that you must use for example Adobe After Effects to combine these 2 renders to 1. The Hardware Renedered pictures only contains the sparks and a black background, but how am I supposed to put the sparks over the actual software rendered image?, the black color just covers everything... What am I supposed to do to make the black area on the image to be transparent, so that I can see the stuff below?