Circuit Connections

HC-SR04      Arduino
--------     -------
VCC      --> 5V
GND      --> GND
TRIG     --> D9
ECHO     --> D10

Green LED   --> D2
Yellow LED  --> D3
Orange LED  --> D4
Red LED     --> D5

All LED negative legs --> GND through 220Ω resistor

Buzzer (+) --> D6
Buzzer (-) --> GND