You need the V-Cast program. Once you have that, you have to install it on your computer, plug in the USB cord to your computer and your phone, then go into your phone and to the music feature. Then choose "Sync Music." It worked for me at first, but mine doesn't work anymore...
Oh, if you find you have problems with it, go to www.vzw.com and download a patch for your phone. It's free.
You can't use your v-cast music as ringtones. I tried, but it doesn't work. Try going to www.mobile17.com. Free ringtones and you pick where the song starts and stops.