Wash your hands in warm water and gently push your cuticles back. Remove your other polish if you have any. Then trim, cut or file your nails as needed.
Paint all of your nails with a base coat. This will protect your natural nails from staining (although the Sharpie will come off) and help you remove the design easier with nail polish remover
Start coloring your non-dominant hand with your dominant one. If you are right handed, color your left, and vice versa. When you're finished, ask someone to do your other hand for you.
Coat your nails with a top coat afterwards. It'll be a lot shinier than if you just leave it, and it will last longer. This is optional.
To remove the Sharpie, simply wipe your nails with nail polish remover to take off the color.