74HC595 (SCLK) Pin 11 -> Pin 13 (D13, SCK) of the Arduino
74HC595 (RCLK) Pin 12 -> Pin 8 (D8, ICP1) of the Arduino
74HC595 (SER) Pin 14 -> Pin 11 (PWM, MOSI) of the Arduino
Note: The bottom-most shift register doesn't show that it is the one connected on the Arduino in the illustration. Make sure this is the one connected to the Arduino!