Continuos Thinking. Help me for that.

I am 20 years old . A girl asked me for sex with me. But I kissed and hugged her and do not sex with her went away from her. Few days after I said no to that and went to college.in college I'm not focusing on studies because it is the first time kissing a girl. I'm thinking asexually things in mind now. But I don't need think that sexual things right now. Because I wants to study well. Please advise me how to forgot or control from it. I want to study hard while reading books my mind diverting to bad thinking. Some times I am loosing my control and doing masturbation. Please advise to stop everything and concentrate on studies hard. Because in this year I want to study MBA work hard in studies. Please sir your advice is most valuable to me. I wants to forgot everything of sexual things. Only studies. Please help me for that.