What libraries and where I need to place them to control a DC motor with simulink using an arduino Mega 2560 board with a motorshield adafruit v1?

I am trying to control a DC motor using an arduino Mega 2560 board with a motorshield adafruit v1. On the web there are some explanations but they are all confusing about the libraries I need and none of them worked. I already downloaded and installed the arduino support package. Creating and running programs with Simulink on the arduino board work fine (as blinking leds), the problem comes when I have to use the shield adafruit v1 to control the motor. I have also downloaded the arduino library AFMotor and placed it in the arduino libraries. Also, the example MotorParty for IDE arduino works fine. Hence the problem is the communication between matlab and the motor shield v1. Thank you.