Your Galaxy Sol has a microSD memory card reader. If your personal computer can also read that card type (Most laptops are so-equipped), you should be able to save a music file
The Galaxy Sol is a smartphone. Most smartphones will let you save any song found online by tapping and holding your finger on it, then selecting 'save.' Once a music file is saved to your media library, tap-and-hold it and select 'assign' from the drop-down menu.
The Samsung Galaxy Sol is an Android phone and there are plenty of free ringtone apps such as MP3 Cutter, RingDroid (open source) and more.
Since your Galaxy Sol is equipped with a sound recorder (also known as 'voice memo'), a very simple technique involves just putting your phone nearby your computer's speakers, playing whatever song, music or sound you would like as a ringtone, and recording it -- you can even use your voice, your child's voice or even your cat's 'meow!' Record it with your mobile and there you go! Unless that function was specifically blocked on the Samsung Galaxy Sol, you should be able to navigate to the ringtones section and choose your new recording as a ringtone. Of course, the quality will not be optimal but, after all, it's free!
More on free ringtones
Here are some of the 100% free ringtones (Samsung Galaxy Sol-compatible) offered here at MartinsRingtones.com:
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