Apple iPad iOS 6.1 - Manual (Page 50)

Chapter 7 Messages 50
Messages settings
Go to Settings > Messages to set options for Messages, including:
•
Turning iMessage on or off
•
Notifying others when you’ve read their messages
•
Specifying a phone number, Apple ID, or email address to use with Messages
•
Showing the Subject field
Manage notifications for messages: See Do Not Disturb & Notifications on page 113.
Set the alert sound for incoming text messages: See Sounds on page 118.