why do i fall in my back bens?

You have to look where your hands are going when  you arch backwards to form a bridge.If not, you might end up on the floor!

who does what?

You may wonder what things do male and female gymnasts do. The females do stuff like the balance beam. the males to things like the rings.

difference please?

In gymnastics, the difference between a bridge and a back walk over are different. I know a bridge sounds wierd, but in a bridge, you stand with your legs apart and have your hands up and arch your back in a bridge shape. In a back walk over, you put one leg in front of the other, hands in the air, and lean back ith your leg in the air and kick it over your head and land facing where you started.