My boss made a p at me and I'm 16?

I'm 16/f. I recently got a job as a busboy/stockboy at a restaurant. The owner's 24 year old son "works" there. Mostly what he does is flirt with the female employees (and all they do is think "Oh my gosh. He's so handsome" in that dreamy little voice that makes you want to puke) and do some paperwork. Basically rich kid with a power trip who likes bossing people around. I think on my 3rd day there, he tried to "charm" my friend who'd been there a week. Even after she said she had a bf, he persisted so I poured a drink on him (The guys wanted to laugh, The guys just look liked "How dare you!"). He didn't write me up or anything (which I thought was odd because he looks like the type to ruin someone as much as he can over bruising his ego). Anyway, it was late one night (the place only opens for dinner) and I had taken my friend's shift because she went to visit her brother out of state in the hospital. I think everyone but him, me and like 3 other people had already left. So I was in the back room with another girl and he walked in, him and I exchanged some sarcastic remarks and the girl left to answer the phone. He closed the door (it opens with a code and automatically locks and you need a card key which I didn't have). He like pushed me against the wall and I could feel him like "be hard" against my body. I told him to let me go (in harsher words which Yahoo answers will probably censor out) and the girl who was working with me walked back in to help finish and instead of doing anything, she just apologized for interrupting and said that the phone call was his girlfriend before walking off. He held me there for like a few more seconds but then walked off. I'm not afraid of him but I don't want anyone touching my body and I don't want to admit it, he is stronger than me even though me and him are about the same height because he's muscular. The whole expierence has just made me anxious about work. The girl who saw it told another guy because after he ignored the next day (because we usually bickered several times a day), the guy joked by asking if we were having a lovers' spat. I don't know what to do. I feel nervous when I go to work. Especially without my friend. What should I do? I don't really care about him getting in trouble for what happened and I don't want people knowing because all they're going to think is that I flirted with a cute, rich guy and changed my mind after it got physical.