How can I learn a back handspring and backflip?

I have a trampoline with a net and want to know how to do a back handspring and flip without taking gymnastics or tumbling. I can do a front handspring on both tramp and ground and a front flip on the tramp. I tought myself how to do those, but i'm scared of trying a back hand spring and flip. How do I do them? what techniques can i use? Thanks