How do I stop masterbating?

I watch pornography most of the time and get horny and tempted to do it. I watch pornography in secret. My brother know I watch porn but my friends and family don't know. When I was in 6th grade. Most of the time, in my classroom. I treat girls like sex objects. When I look at girls in my class during 6th grade I stare and try to look at part of their nudity and become frozen and shy. I still masterbate and look at porn. Thanks. I masterbate in my gray pajamas on the computer and in the washroom. Now, every time I wear them or touch them. I get horny images in my head.