you play it and race.
Bit of advice grab a hammer and smash the wii up
Win first place on the cups you already have. They'll unlock the new ones.
Do ALOT of races do the Grand Prix and othre missions to unlock new ones.
First beat 2 cups and you unlock a new cup
beat the cups and you should get new places to race
To get new courses, you have to unlock cups (2 in the nitro and two in the retro) by getting gold trophies in the starting cups. After you have unlocked all the cups in 150cc and gotten gold trophies in them, you can unlock Mirror (known as 'extra mode' in Mario Kart 64), which is flipped courses in 150cc mode.
No new Mario kart has been announced for the DS
A new installment for Mario Kart was announced on the Wii U
Win 1st place on the courses you already have. They'll unlock the next ones.
http://answers.Yahoo.com/question/index?qid=20080331205918AAmfc4L
i think you should get Mario kart wii! because there are a bunch of exciting courses to unlock and the characters are really fun to unlock you could also do battle on there and if you have internet connection you could play people from all over the world and make new friends!
you have to win first every time you play then you will win stuff !! like new ppl ,new kart and bikes,and new tracks of course and that's all i can tell ya
keep playing it until you get a higher grade