Can I plead not guilty?

I was in school; and my shorts were too short and these teachers always har me and never really talk to other people about the dress code. Anyways; I was angry and said I was just going to go home to the cop person and the itant principal because I didn't want to change at first. Than I went by my locker and i was just gunna put on my sweatpants because I had changed my mind. && The police cop was right next to me and I grabbed my stuff and than swinged closed my locker and said that Ima bout to put on my sweatpants and I raised my voice by a little bit saying get away from me. && than he handcuffed me and gave me a ticket for disorderly conduct. I think I'm not guilty but what do you think?. & what do u think will help me in court?