Plug it into a USB port (must be powered). Look for the external drive that mounts in the Finder -- mine was called 'Untitled.' Put your music files here: Untitled/Music/Artist/Album/, then eject the disk. (Replace Artist and Album with the proper values for the music you're transferring, of course.)
Make sure you use MP3s. I thought this didn't work at first, because I used AAC files, which the Dell does not support.

