Thanks heaps for reading!

I am terribly unfit. I want to completely change my body, because i am sick of being so careless. I thought i'd throw in this too:

Im 13.
Im 6ft. (Yeah, i know...)
Female
Very bad flat feet
Dont do PE or Sport (due to pain.)
Had Osgood Shlatters in grade 5, and was forced to sit out of PE for a year. Thats how i got so unfit.
I have a weak back. If i bend too much (or even if i bend down too quickly to pick something up form the ground) i pull muscles, and that really sh!ts me because i do it alot.
My build is supposed to be tall and slim, but i have big hips. It looks weird ause my arms and legs and shoulder/collar bone area is skinny, but i have a belly, and want to get rid of it.

I dont want to do proper classes at a yoga place or anything, because my mum probably wont pay, and it will be embarassing, cause im so unflexible. I can barely cross my legs :$

I just want to know as much as you can explain about Yoga. Thanks so much!

xx