How well is Asana Yoga?

how well will it get me into shape.. is it one of the good types of yoga? I am already pretty skinny but i want to be more toned and muscular. haha i also want to know if it will give you a good butt cause that would be awwesssomme:) i have been doing a lot of situps but idk they dont feel like there doing anything anymore maybe its just cause im used to them

- im fifteen by the way if it makes a difference-

i think u shld eat properly cuz u need to have muscles to get toned !!! aasanas are really good and i d only suggest u to do tht !! google some assanas and consult with an instructor and strt practicing thm …. in addition also do breathing excercises …. thts used to release toxins frm ur body !!