just learn to backflip on trampoline without bouncing, get a good and fast spin and tuck, when you get good without a bounce get some mats and put on floor and go try backflip, if you get your confidence good enough and tuch a little then you will be ok, u can never land the first backflip or frontflip, never, your amazing if you do.
but give that ago and mabye you get lucky within the first 10 or 20 attempts u might do one !!!