You have to win the indoor, outdoor, and combined events in series mode. Do this for both the 125cc and 250cc classes. There should be new tracks which will be unlocked in freestyle mode.
List Of The Tricks
"NOTE" all these tricks are with default controls. Must be done in the air. Best in freestyle mode.
Trick - Code
can can - R2+square
no footer can can - R2+X
no hander - R2+down+L1
nac nac - R2+L1
super mac - R2+left/right+square
recliner - R2+down+X
scorpion - R2+up+X
backflip - R2+up+triangle
rodeo - R2+R1
toe clip - R2+R1+up
saran wrap - R2+R1+down
nothing - R2+L1+up