Trouble reaching orgasms

I feel like I should give some background info before getting into this. I stumbled unto sex by mere curiosity. So I learned things as I went or from what my friends told me. I never really dated until somehow I was already in the relationship. From my experiences guys were pretty selfish so I never knew an orgasm until I had my second boyfriend. It just happened at first and then I had to really put some effort into it or just resign to the fact that it wasnt gonna happen.