Sending a Message - Screen 1
It is generally considered polite to send a message to your realm when you first join. This tells them that you at least have some idea what you are doing, and that you are willing to talk.
Anytime after you have logged in, click on the "Messages" button in
the top left of your screen.
For your first message, you want to say hello to everyone in the realm. Select "all players of your realm" and click on continue.