Plug the potentiometer in your extensions port. The left and the right pin to GND and + 5 V and the pin in the middle to Pin 19.

This code plays a permanent rhythem, which can be controlled by the potentiometer.

Plug the Photoresistor in the extensions port to GND and to PIN19.

This code plays a permanent tone, which get as higher as less light is hitting the photoresistor.