The Backflip
[1] First, practice your set by jumping with tremendous arm swing to help your height. This requires you to bend really low before jumping. Keep your arms straight and experiment to find the most effective swing. Your arms should always end up by your ears at the very top of your jump.
[2] Once your set is feeling high and comfortable, you should start letting your arms push a little bit past your ears. Do it very forcefully so as to send your chest backward a bit. The backward motion should only occur at the very top of your jump, just when you start to hang.
[3] When you have reached the point where it is unsafe to continue the last part because your chest is thrown so violently backward that you could land on your head, it is time to complete the move. At the same time as your chest starts to move backward(top of the jump) bring your knees to your hands and into your chest. It sounds hard but it is supposedly easy if you do it at the very highest part of the jump. Once this is done, you will turn over with the force of hte arm lift that has already been made. You just ahve to get the hang of opening up and landing on your feet.
Tips: Learn a backflip on a thick mat or a mattress. If you can, get a friend to stand next to you with a hand underneath you. In case you bomb out, they can stick an arm under your chest or back and turn you to your feet. If you do it on a mattress though, it is supposed to not hurt at all if you land on your head, but you'd have to find out for yourself.