For men: ?

Okay, so my boyfriend and I have been together for three years. We have been taking things slowly, upon my request. Recently though, things have sped up real fast, and we are engaged now. So he has performed oral on me several times lately, and it was great! But now he is upset because I don't give back. This makes me feel really guilty! And I'm really really really nervous, and I have no idea where to start. Before we got together I was a virgin, and lived a VERY sheltered childhood. I want to make him happy but I'm not even sure where to start with the . Could someone please help me? Remember, I lived a sheltered life