It doesn’t.
There is a reply button in the bottom right of each reply on a post. Clicking that should let you reply to a person. If that doesn’t work, then quote what you’re replying to, or @ mention the person, @ggbutcher so they get a notification 
It doesn’t.
There is a reply button in the bottom right of each reply on a post. Clicking that should let you reply to a person. If that doesn’t work, then quote what you’re replying to, or @ mention the person, @ggbutcher so they get a notification