To do a back flip you hold back when you go off of a jump.  But
backflips are very slow, so there is not that many ramps you can do it
off of. sp, go to freeride  GLACIER RESORTS. When you get there turn
right at a diagonal slant. You will see to simple buildings turn into to
these and there you are the biggest ramps on the game! to do a back flip
do a wheely when 3/4 way down. then off the jump pull back and you do a
back flip. front flip when off the jump go like your doing an endo but
keep on going to the front.