In theory, the design isn’t hard, just requires a very steady hand.
1. Paint two coats of a white base.
2. Using a black fine-tip polish, begin your stripes from tip to base, staring with a French manicure style strip across the top. Work your way down, making your black and white spaces totaly equal. If your lines aren’t perfectly straight, don’t worry–you can always go back over it after with the white to even things out.
2. Alternate your starting color with every other finger, meaning if the tip of your nail was black on the thumb, leave the tip white on your index finger and start the black a little farther down.
3. Once you’ve finished the black on every finger, go back over with white (preferably a fine-tip brush) to make the stripes even.
I haven’t done this, but many people find using stickers (usually cut-up pieces of circular reinforcements) allows for a perfect, easier, cleaner stripe. I’ve never had the patience to cut and fit stickers to my nails before, but it might be a good alternative if you aren’t so steady of hand.