I used Preferences to change my default library to an external hard drive. The drive has a folder called iTunes Music, where all the songs are located, most of them in folders. I've set that iTunes Music folder as the destination, but the songs in the folders do not show up in iTunes. There are other folders on the hard drive, including something called iTunes Music Library.xml, and another library.xml file. Are those related to getting all the music into iTunes, or do I have to do something with all the folders in the music library, or am I doing something else that is pathetically wrong?