No he has an inline USB interface, they are so small it's just a cord for the guitar with a small dongle on the line. It converts the guitar signal to USB and GB or whatever DAW sees it as a MIDI input.
Go to Applications>Utilities>MIDI
Make sure the system input is set to your USB Midi converter doodad, and the output is set to System out, some of those guitar recorders have their own headphone out, so make sure it's set to SYSTEM out, then you will hear out of the monitors like you do with your snoball. Which brand 1/4 to USB do you have?
Then, in Garageband, when you are recording, make sure you have monitoring set on, the control is somewhere near the bottom right hand corner.