When people think of music, most think of MP3 or WAV format files. In fact, for the most part, MP4 files are used for videos. However, music does come in MP4 format and is most easily found from files downloaded over iTunes. Downloading MP4 files is no different than downloading any other kind of music file, but you also run the same legal risks if you don't take the time to download the files through legal meas.
Downloading mp4 Music
Open your file sharing or P2P (peer-to-peer) program.
Search for the particular files you are looking for. In the drop-down menu that is normally located near or under the search bar, select ".mp4 format" or ".mp4 only" under "file options".
Allow the program to search the Internet. When it finds a file that matches your specifications, it will list it for you.
Select the files you wish to download. These will go in the program's queue and will be downloaded to the specified location on your hard drive.