I cut out random (odd-shaped) pieces of paper - next time I will use wax paper or something that doesn't stick as well. Then I placed the pieces all over the cake to leave open spaces to color. I sprayed the whole cake with green spray and let it dry for a few minutes. Then I CAREFULLY removed the odd-shaped pieces I had cut out and placed on the cake. I had to be more careful with spraying the black - just to color the areas that were white.
I compeltely messed up the lettering. It was my first time. I think next time I will buy the candy letters and use those instead of trying to freehand it.
My son and his friends LOVED it though. Oh, and I should mention, I made two rectangular cakes and froze both of them. Then I cut off the bubbled portion of the top of each cake to make it flat. I put a layer of filling (homemade) on the top of the bottom cake and then added the second cake to give it height.