The VG Resource

okay guys i am going to need all of your help on this

i have never ever sprited a human custom before, in any capacity. i know a little bit about anatomy, i'm trying to do the latest pixeljoint challenge.
i realize there is hardly anything there, that's why i need your help.

well, you'd actually should give us a context to begin with. if you lack one, it could be (reading upon the challenge's rules) a kamen rider cosplay avoiding its fanboys?

spiderman backflippin' over something, i added a leg. i don't think it looks right.

Legs are not noodles, they have bone.

You might want to restart completely and try to use a stick figure rather than blocks as a base. Your current base lacks a neck and the limbs don't make sense. I think that experimenting with a stick figure until you find a good stance / pose is much easier.
Here's a little sketch of mine to show what I mean. It's far from perfect (I'm not that good at making special poses myself), but you should get the idea.

Watch videos of people backflipping to get an idea of what goes on during a backflip. Generally, the legs only bend backwards during a front flip. With a backflip, one or both of the legs is kicked forwards.

The Only Way the Legs would bend that way would be if it was a gainer of some kind, if it was a backflip the legs would be tucked up