helpp!!

ok so i kinda don't wanna explain the whole sexuality thing so please don't ask but.... the guy im basically fucking is scared to eat the nani because he's never done it so he doesn't know how and plus you know the whole what comes out of it thing but now I've gotten him to agree. But here's the thing i told him I'd teach him on me but the thing is idk how to really tell him, now i have been with a girl like we were engaged and all so I've became like a pro but I've never had to explain it so how would i explain to him?