Do you have a PC or Mac? You can always hook your phone up to your PC via USB and then drag and drop music files using Windows Explorer. I also suggest installing Google Music Manager onto your computer, which will allow you to upload your entire music library to your Google Play Music library in the cloud. You will then be able to stream that music to any device that has Google Play Music or any computer browser. You can also temporarily download the music to your devices, as well as permanently downloading a copy of the music to any other computer.