How to Do a Backflip on the Ground
Get on a proper gym floor with a mat, preferably till you get into the groove. If not, make sure you are in a reasonably open area with a soft surface. But make sure that the floor is not a concrete one, and has no obstacles. You will only be giving an invitation to injuries.
Now, as the backflip involves a lot of limb extensions and stretching, if you are a beginner, it is crucial to do some stretching. Make conscious efforts to warm up and stretch all the muscles of your limbs, chest, and back. You do not want to tear your ligament or pull a muscle while doing this.
After you have stretched thoroughly, stand straight with your arms above the head. Keep your feet shoulder-width apart. Ensure that you have a proper balance if you do not want to land on your head with a backflip gone terribly wrong.
Now comes the important part. Here, what you need to do is, swing your arms first down and then back, squatting for a jump at the same time. To get a good push off the ground with both feet, let your knees bend at a 90-degree angle.
Continuing with the previous movement, lean back and tuck your knees in your chest, at the point while you are reaching the peak of the jump. This is pivotal for getting the momentum and tempo for flipping backward. If you do jumping exercises, they may prove helpful for getting the act properly done.
Three-fourths of the way in the rolling process, stretch out your legs and land on your feet. This timing has to be impeccable, or else there would not be any backflip. But don't worry, you will get it with practice!
For reducing the shock and the impact of landing, and also to maintain balance, bending the knees while you land is necessary. There is no harm in placing your hands on the floor if you feel you might fall.