Take the USB cable that came with the phone, plug one end into the phone, plug the other into the computer, let the computer mount the phone as an external drive, and use the computer's file explorer to copy paste the music?
I'm most definitely NOT a VZW employee. If a post answered your question, please mark it as the answer.
Download the free Zune software to your computer from zune.net. Sync your music library to Zune, then connect your phone to your computer using the USB cable and use the Zune software to transfer music to your Windows phone.