You may want to chat out loud to blend in with other Avatars or say "hi" to someone you meet. Your message will only show in the area to where you at like on the image below, only the two Avatars on the image can read the message. To do that just check on the guide below.
To Chat in Public - Click the "Chat in Public button". Then type your message in the "chat box" and hit "enter key or return key" on your keyboard.