Deleting all the same but non-contiguous color to transparent

I want to make all the white but many non-continuous areas AND the background of a document transparent with key commands. Does anyone know this? I have a document which shows up as black and white but I want to remove the white so it doesn't show up for sublimation printing on dark. I only want the black area I have designed to show up reversed as white on the dark printing surface. Thanks much, J J