Turn the Bluetooth feature "on" in order for the phones to be searchable. Most Bluetooth settings are located in the phone's "tools" or "settings." The subcategory should be entitled "connectivity settings." Find the Bluetooth category and click "enable."
Pair the two phones. This should always be done by the sender's phone. Go to your Bluetooth settings and select "add device" or "search." Once this is done, the phone should begin to search for the device you plan to pair with. When that phone is found, click "add." Then the phones should ask for a passcode (which in most cases is 0000 or 1234).
The pairing phone will want to know if you accept the add. Select "yes" and enter the same exact passcode. The devices should now be paired.
Go to the ringtone you would like to send. Click "options" under the actual ringtone and select "send via Bluetooth." The ringtone should begin sending to the pairing phone. The other phone should give some type of indication that the ringtone has been received.
Turn the Bluetooth setting to "off" on both phones.