Your U11 Eyes has a microSD memory card slot. If your personal computer has a slot for that card type (Most laptops are so-equipped), you should be able to save a music file
The HTC U11 Eyes 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 (HTC U11 Eyes-compatible) offered here at MartinsRingtones.com:
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