How do u masturbate.??

I'm 19 and never had an oragasm before or came at all.! Sometimes I feel like something is wrong with me lol all my friends have came before n I never have. How do u make yourself cum while having sex with a guy? My bf gets mad cus I don't cum n he's a good size n says I'm the first girl he can't make cum lol I feel bad cus I want to give him that pleasure of making me cum but idk how to do it.! N I want to know how it feels. Please comment ladies on how u get ur self to cum or what tricke helps u get there!