Click the arrow at the right hand side of the screen, in the middle. It shows information about guild battles, donations, level ups and of course we can chat there.
To say something, click on the bottom line and type, then press enter to post the message so we can all read it.
To whisper, click on someone’s name and @ is displayed at the bottom, in front of their name. You can also manually type the @ symbol, followed by their name, and then a space.
Whispers will show the player name in purple with the message in pink. Those are private messages that only the sender and recipient will see. When it displays the message you send, it displays your local time for some reason, with an @ symbol in front of the recipient’s name. When you receive a whisper, it displays the server time, without an @ in front of the sender’s name. Or you can send mail to that person instead, your choice.