Use a marble pastry board, and if you can't get that, a smooth piece of glass will work. Place a towel on your worksurface, then put the marble/glass on top of that. You will also need some putty/spackle knives - for stripes, use ones that are 1" wide or less. You'll need a wider blade for making the curls themselves. Thin striping can be done with plastic cake combs.
Using candy melts (Merckens, etc) is a lot easier than using real chocolate; the tempering can be a pain in the butt. Melt your wafers and place the cup/bowl in a pan of warm water to make sure it stays liquid. (A benefit to Merckens is that they stay "melted" even after it cools enough to stick your fingers in - hey ma, look! No burns!)
Anyway, pour some melts on your marble, spread it thin, wait for it to set up a bit, and then scrape the first color off with the cake comb so you can see the marble underneath. Pour another thin layer of the second color on top, spread it out, wait for it to set, and then run the wide putty knife along the surface, away from you, to make the curls.
For large, fat curls, make sure that there is less of an angle between the marble and the knife handle (about 15-20 degree slant). For long, skinny sticks, you want a bigger angle (about 40-45 degree slant). Also, if you're running the fat curls, you want a thicker layer of chocolate on the marble than if you are doing the skinny sticks.
Anyway, run the knife, make the curls, and when they're the size you want, leave them on the marble to finish setting up.
Whew. Hope that helps! I don't think I'm forgetting anything, but you know where to find me if you have questions.