How can I be a resource to my son?

A little background on the situation. Father of two sons and one daughter. For my two oldest children who are straight I'v had the talk with them and everything been fine. My youngest son who is 15 came out and told me he plans to be sexually active. I want to be a resource should I need to answer any questions he may have about practicing safe sex. The thing is I don't know what that looks like in a gay relationship. I'm not sure what I would say if he were to ask me specific questions.