How do you even make a friend?

How do you even make a friend? I don’t know how people have friends. I don’t know how to make one. I don’t know when you hit the mark of going from an acquaintance/co-worker to a friend. I don’t even know what being a friend feels like. I’ve never had one. What do you even talk about? How do you break into a social circle? How do you even met people to begin with? Am I the only person who’s always felt like I’m on the outside looking in?