Your Overture 3 has a microSDHC memory card slot. If your personal computer is compatible with that card type (Most laptops are so-equipped), you should be able to save a music file
The ZTE Overture 3 is an Android phone and there are plenty of free ringtone apps such as MP3 Cutter, RingDroid (open source) and more.
More on free ringtones
Here are some of the 100% free ringtones (ZTE Overture 3-compatible) offered here at MartinsRingtones.com:
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