Your Studio G4 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 BLU Studio G4 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 BLU Studio G4) we offer:
Free Horror Ringtones Free Ghost Ringtones Free Ringtones-a-gogo Free Techno Ringtones Hear All Our Free Polyphonic Ringtones