Your A77 sports a microSD memory card reader. If your laptop or personal computer can also read that card format (Most laptops are so-equipped), you should be able to transfer a music file
The Oppo A77 is an Android smartphone and the Android market offers a bunch of free ringtone apps such as MP3 Ringtone Maker, RingDroid (open source) and more.
Here are some of the free ringtones (compatible with your Oppo A77) we offer:
Free Horror Ringtones Free Ghost Ringtones Free Ringtones-a-gogo Free Far West Ringtones Hear All Our Free Polyphonic Ringtones