How do you orgasm ?

I'm 20 and stuck with a problem : I don't know how to orgasm... I hardly ever masturbate, because I feel weird when doing it, as if I had no motive or so... Therefore I never had an orgasm by myself... And my bfs couldn't do it for me either, because I don't know why but there always a kind of border where I'm super excited and all but can't go any further than that... I don't know if somebody can help me understand how to cross that kind of border in order to finally have an orgasm ?