Our schematic consists on 3 elements which are: Photoresistor (LDR), Piezo Buzzer, 1 – 10 kΩ. The LDR can be connected any way you want because doesn’t have polarity. For resistance you can use from 1 ...

Schematic: Below you can see a schematic image to facilitate the wiring of cables from the microcontroller to devices, both input and output sensors: ... Connect the PIR sensor, LED, and piezo buzzer ...

You can use basically any pin, as long as they can be used as digital pins (pins A6 and A7 of the Arduino Nano and mini are analog only). Just remember to assign the pin number to the buzzer variable.