Choose "Wreckin' Racing=" then "Championship" and enter the h3 "REFLECT". Now go to the main menu again and choose "Wreckin' Racing=" again. This time choose "Practice". At the track selection screen you should see the new track.
Follow the steps above but enter "DAMAGE" as your h3 instead.
Select Number of Racers
Follow the steps for 'Secret Track' but enter the h3 "NPLAYERS" instead.