how'd you do this ? :O
I'm guessing it was something like this, with all the bright random colours changed to either black or white as appropriate:
There's more to it than just that (and Joker has obviously paid much more care and attention with the positioning than I have here), but without getting bogged down in the detail it works as a general idea of how pictures like this are put together. There's almost always a lot more going on than meets the eye.