On the AndyMark product page the second picture is the wiring diagram:
http://www.andymark.com/product-p/am-3010.htm
- 12 volts input power and ground from the PDP go to both the Arduino and the DC-DC converter.
- Output power and ground from the DC-DC converter goes to the LED strip.
- Wire the Arduino signal ground to the ground terminal on the output side of the DC-DC converter.
- Wire the Arduino Digital IO pin to the LED strip signal wire. Make sure your code has the correct IO pin number or it won't work. The example code has it set for Pin 5.