Connect the MIDI cables to the MIDI output and input port on the back of your Yamaha Portatone keyboard. Run the MIDI wires to the MIDI side of the USB-MIDI interface. Ensure your computer is switched on. Connect the USB wire from the opposite side of the USB MIDI interface to the USB port on your iPad or Macintosh computer.
Press and hold the “Demo” button on the keyboard to bring up the PC mode, if your keyboard has one (the PSR-E303 does, for example). Locate the demo button by looking to the top, right corner of the front display, near the “Voice List” for the instrument. Hold the button for longer than a second to bring up the option.
Press the “+” and “-” buttons to select the desired option. Choose “PC1” for an ordinary Macintosh and “PC2” if you are using an iPad. The “+” and “-” buttons can be found either side of the number “0” on the number-pad. This brings up the recommended MIDI settings for the various devices. Alternatively, you can manually set “Local Control” to off and “External Clock” to "On" by repeatedly pressing the “Function” button until the options appear on the display screen, which can then be edited using the “+” and “-” buttons.
Click on a software instrument on Garageband and play your keyboard to test it out. You should hear the software instrument from Garageband play the notes you pressed on your Portatone keyboard.
Press the “New Track” button in the bottom, left corner of the Garageband main screen. This icon looks like a "+" sign. Select a “Real Instrument” if you wish to hear the sound that would be produced by your piano. This will display what you play as a wave form. Alternatively, select a software instrument and use your Portatone keyboard as a controller for the instrument.