1. Connect your Casio CTK-4000 to your computer using a MIDI cable.
2. Install Casio MIDI Manager on your computer if you haven't already.
3. Open Casio MIDI Manager.
4. Click the "File" menu and select "Open."
5. Select the MIDI file you want to load onto your CTK-4000 and click "Open."
6. Click the "Transfer" button.
7. The MIDI file will be transferred to your CTK-4000.
8. Once the transfer is complete, click the "Close" button.
Method 2: Using a USB Flash Drive
1. Format a USB flash drive to FAT32.
2. Copy the MIDI files you want to load onto your CTK-4000 to the USB flash drive.
3. Insert the USB flash drive into the USB port on your CTK-4000.
4. Press the "Function" button and select "Load."
5. Use the arrow keys to navigate to the MIDI files on the USB flash drive.
6. Press the "Enter" button to load the selected MIDI file onto your CTK-4000.
7. Once the MIDI file has been loaded, you can play it by selecting it from the "Song Bank" menu.