guys I'm bi
Do you need to tell them?, would you need to tell them if you were straight?
Facebook like everyone else.
I don't know you or your friends, so neither I nor anyone else here can answer that as effectively as you can, but I think it should include "Oh, bi the way..."
Phone, text or speak with them.
Don't tell them..show them!
By being yourself! Show them that you are a sexual person, compliment male and female beauty and they will realize eventually.
You don't need to if you don't want to.
Alright, start like this: "some people like boy bits, some people like girl bits. I want the best of both worlds!"