The sponge method is really easy to do and there are a couple ways to do it. Again, if I can enlist the aid of a camera person I will try to show you all how to get it done. Till then I will right a mini instructable:
You need whatever can of spray paint you want to use, a glass, or plastic bowl and a Faux Artists sponge like from a hobby store. Granted you could probably use an ordinary sponge but these sponges have varying size holes so it doesn't turn out as uniform.
Apply your base coat(s)
Take the sponge and tear a chunk off of it about the size of two or three of your fingers curled up
(use a different/clean piece for each color)
take the bowl and spray the paint into it, letting it pool in the bottom.
Dip the sponge in the paint. (I recommend using only one side or end of the piece to wet with paint, then use the clean side to dab off and spread the paint lightly around. When using this method, the sponge should be "dabbed" onto the surface and lifted straight up off the surface. Do NOT move the sponge while it is in contact with the surface or you will end up with a large smear.
It applies here especially that you can add but it very hard to remove. So apply paint sparingly.
Any questions post here and PM me.