How do u "come out of the closet"?

im bi. only 3 of my friends kow and 2 of them r guys.one of them said i should "come out of the colest" but im rely rely nevus 2. im not even in high school yet and i have another year or 2 of gym cl. i don't kow if i should come out and if i do how. i don't like people making fun of me. and if u have a problem with me being bi don't right it.