If your music is owned by you and not on subscription, the files will be in unprotected aac format. If so, simply hook up your phone to your computer, switch your phone connection to "file transfer" mode in the notifications window, then drag and drop files to a folder of your choosing on your phone in Windows Explorer. Or, if you have a micro SD card, you can insert that into your computer with the same instructions to load them onto that.
After you transfer files, you need a music player. Samsung offers the "Samsung music" player in the Samsung app store which is novelty good. It should auto import any music files you have.
I actually use itunes and transfer to my S20. Super easy. All of your music should be in files, and if you ripped cds they'll all be organized by artists or albums I believe in your music or itunes folder. Plug in the S20 and drag and drop those files to the media/music folder on the S20. Mine may be a bit different because I keep all my music on the SD card so I think mine is named media whereas yours might be named music. Hope that helps.
