When you turn the DS on, go to "System Settings" at the bottom of the screen (it is the picture of the DS). Go to "Personal Settings" (the picture of a person) and tap the color scheme (the top option, with the squares). Select a color, press A, press B(2), then press A again. Start the DS again, this time starting the game. Anytime you do a spine transfer, flip, roll, etc., there will be a trail of color coming out of your board. That color should be the one you selected.