You can google limewire and download the program, like what rainbreed said. there, it can be like google, all you have to do is type the title of the song and maybe the artist - who sang it - to be more specific.

Or if you are familiar with torrents, you can download albums from artists, even their music videos.

Go to www.thepiratebay.org for searching music, and utorrent.com to download the program.