If the 9 Volts Battery came with safety cap, remove it first. The Battery Clip should only allow you to snap it to the Battery in one orientation for the correct polarity (Picture 1).2. Connect the Red Lead to the Positive Rail on the breadboard.
See Picture 2.3. Connect the Black Lead to the Negative Rail on the breadboard.
This would instantly supply power to your light detector. The LED on your circuit may or may not light up depending on your Variable Resistor but do not worry about that, we will configure the circuit in the next step. Successful completion of this step should produce something close to Picture 3.