Slide your finger downwards starting from the top of the screen.

Tap the menu icon.

Tap Settings.

Tap Notifications.

Tap the field next to "Received notification" to turn on the function.

Tap the field next to "Play notification sound" to turn on the function.

Tap Notification sound.

Tap the different message tones to hear them.

Once you've found a message tone you like, tap APPLY.

Tap the Home key to return to the home screen.