Below you will find the circuit schematics and list of parts for this setup, and also a video showing step by step how to build the circuit on breadboard.
Components list:
T1 - BC547
R1 – 330Ω
R2 – 56KΩ
LDR - LDR
L1 - LED
I used a 56KΩ resistor in this example for increased sensitivity to darkness. You can use a 100KΩ POT to make an adjustable sensor.
Step by step video guide on how to build the circuit according to the schematic above: