The DP-90e comes with hundreds of built-in songs; however, you can also load your own music onto a USB flash drive, and play it through the DP-90e speakers.
The DP-90e can read both standard MIDI files, and audio WAV files.
Here's how to do it:
1) Plug your USB flash drive into a computer, and load your favorite music (in Standard MIDI file form, or WAV file form).
2) Unplug your USB from the computer, and plug it into the piano (the USB port is located underneath the far right side of the keyboard).
3) Press the [Song] button
4) While holding down the [Song] button, use the [-] and [+] buttons to select the USB flash drive category, indicated by an "S" on the left side of the screen.
5) Once you have selected the "S" category, use the [-] and [+] buttons to select your desired song within that folder.
6) Press the Play/Stop button to begin playback of that song