Find "Phone"
Slide your finger down the display starting from the top edge of your phone.
Press Settings.
Press Settings.
Press Notifications.
Press Phone.
Turn on ring tone
Press the indicator next to Sound to turn on the function.
Select your ring tone
Press Tone.
Press the different ring tones to listen to them.
Once you've found a ring tone you like, press Back.
Exit
Slide your finger up the display starting from the bottom edge of your phone to return to standby mode.