Scared to receive oral

My boyfriend wants to go down on me but I don’t let him because I feel like he doesn’t really want to I mean I don’t see how it benefits him so idk why he would want to and I wouldn’t know what to do while he’s going down on me, like do I just lay there or what? Then if he stares at me while doing it that will make me so uncomfortable. How to I relax and let him do it