How can I start playing barre chords?

I've been playing guitar almost a year now. I have tried to play barre chords but it doesn't seem to work no matter how much or how long I practice. I've had strings cut into my fingers because i thought i wasn't pressing down hard enough. I've tried just about everything. I sill get a buzzing sound if any sound other than the sound of muted strings. can anyone tell me what im doing wrong. I'm a 16 yr old girl and i have small hands anyway. Can anyone tell me what im doing wrong?