Welcome to Android Central! Are you copying the music files to the phone and trying to get them to show up in the Google Play Music app? What directory are you copying the music files to?
I would strongly recommend uploading all of your music files to your Google Play Music library in the cloud. This way, you can access all of your music from any device that's logged into your Google account, and you can download the music for offline listening as well. There are two ways to upload:
https://support.google.com/googlepla.../1075570?hl=en https://support.google.com/googlepla.../4627259?hl=en
