Super Mario Kart

How to beat Super Mario Kart Wii?!?

So me and my boyfriend just bought a Nintendo Wii about a month ago, it came with Super Mario Kart Wii. We love playing it and it is so much fun! But it's getting old because we don't know how to open up new Cups, and characters, etc. We tried beating the ghost, the grand prix, and nothing.
How do we get new levels and stuff?!? please help!!

New levels are unlocked by beating the grand pix races in single player mode. As for unlocking the other characters, see this list:

Baby Daisy - Earn at least a one star ranking in each 50cc Wii Grand Prix cup races
Baby Luigi - Unlock eight Expert Staff ghost data in Time Trial mode
Birdo - Defeat 250 people in online racing, or play Time Trial mode on sixteen different courses
Bowser Jr. - Earn at least a one star ranking in each 100cc Retro Grand Prix cup races
Daisy - Win the 150cc Special Cup
Diddy Kong - Win the 50cc Lightning Cup
Dry Bones - Win the 100cc Leaf Cup
Dry Bowser - Earn at least a one star ranking in each 150cc Wii Grand Prix cups
Funky Kong - Unlock four Expert Staff ghost data in Time Trial mode
King Boo - Win the 50cc Star Cup
Mii (Outfit A) - To play as the Mii associated with your profile, win the 100cc Special Cup
Mii (Outfit B) - To play as the Mii associated with your profile in a different outfit, play through and complete all thirty-two time trials
Rosalina - Have a Super Mario Galaxy save on your Wii and race 50 times OR get 1 star in the 8 Mirror Mode Cups
Toadette - Play Time Trial Mode on all thirty-two courses

And for all of the unlockable karts/bikes (and some other tricks), check this site: http://cheats.ign.com/ob2/068/949/949580.html

Super Mario Kart (SNES) Gameplay