How to program a CAN-BUS arduino shield to control the car's headlights ?

My project is to control car headlights using voice recognition. I have successfully controlled some LED's using the EasyVR arduino shield and an arduino MEGA. Now I want to take control of the lights using the CAN-BUS arduino shield.

Because the car that I own doesn't have an OBD-II connector, I am using two arduinos with two CAN-BUS arduino shields making one a sender and the other a receiver. Now I don't know how to program the CAN-BUS arduino shield to make a simulation of the car's headlights ?

CAN-BUS shield that I am using : https://www.sparkfun.com/products/10039

Arduino mega : https://www.sparkfun.com/products/11061