Your text messages can be sent as either regular text messages or iMessages. iMessages can be sent to phone numbers or email addresses if the recipient has a device which supports iMessages. Remember, you need to activate your Apple ID.
Just so you know...
Please select the red text to see instructional images.
Turn iMessages on or off
If you're asked to log on, log on with your Apple ID.
Press the indicator next to "iMessage" to turn the function on or off.
Turn sending of read reply on or off
Press the indicator next to "Send Read Receipts" to turn the function on or off.
If you turn on read reply, the sender is notified when you've read an iMessage.
Enter email address
Press Send & Receive.
Press Add Another Email....
Key in the required email address and press return.
Press Messages to go back to the settings.
You can key in an email address which others can send iMessages to.