Of course you may use any color you want; these are the polishes I used:
Orly Mysterious Curse
Using the make-up sponges, dab on the second color 3/4 of the way on your nail, starting with the tip of your nail.
Then, sponge the second color 1/2 way up your nail from the tip.
Starting at the tip, sponge the nail polish 1/4 of the way.
Add a top coat and you're done!