First dowload the arduino IDE and write your code. In my case the buzzer and led will activate in beeps together, and as the distance decreases they will gradually start beeping faster. (arduino.cc)

You can download my code to get started with, from here: goo.gl/MHWDy . For those familiar with java, coding for arduino is very similar. For more code help visit arduino.cc

Connect the led to ground and pin 12.

Connect the buzzer to ground and pin 8.

Connect the 5V on the arduino to the VCC on the sensor, and the GND on the arduino to the GND on the sensor.

Connect pin 4 to Trig on the sensor (purple), and pin 2 to Echo on the sensor (yellow).

If you want the system to be constantly running you can connect the battery to the clip and then to the arduino board.

Otherwise you need to split the ground into two. One to go into the rocker switch and the other to keep going to the board connection.

Ground wire FROM battery clip {connect ground to gold connection}. Power wire (red) FROM battery clip. Power wire (purple) TO board connection.

Ground FROM battery clip, and power (purple) FROM rocker switch.

Now you need to solder the connections in place. To do so I would recommend using male and female pin connections so you won't solder directly to the components.

Also I would recommend using heat shrink tubing to cover all open connections and soldered areas.