I would start by bouncing onto your back then trying to roll or bounce off your back onto your feet. Then try a bit of a higher jump and get comfortable with going in a backwards rotation. Then honestly you just gotta send it buddy.

Idk how you did but i practiced in to a foam pit and then on to a matterise and then the floor

You can practice with a coach in trampoline park or try to jump from 1, 5 m into water

Start doing like a reverse round off then slowly get more and more arched and do it. It’s all about committing to the backwards rotation, you can do it!