How do you load songs to casio ctk-4000?

To load songs onto a Casio CTK-4000, you need to connect the keyboard to a computer using a USB cable. Once connected, use the appropriate software, such as Casio's Song Book or MIDI software, to transfer MIDI files to the keyboard. Be sure to follow the specific instructions in the user manual for file formats and transfer procedures to ensure compatibility. After transferring, you can access the songs directly from the keyboard.