Dimmer control over raspberry and arduino uno

I have bought a light dimmer from Keda electronics: http://www.ebay.com/itm/AC-LED-Light-Dimmer-Module-Controller-Board-ARDUINO-RASPBERRY-Smart-Home-/111764492631
My setup is following:
Dimmer is connected to arduino uno on D2, D3, D4, D5 pins and arduino is connected to raspberry over tx rx and usb connection.
I have uploaded dimmer code to arduino and when I make an input in raspberry minicom, dimmer is working.
Problem is that I have no idea how to write a code in openhab2 to make it work. I am trying 5 days already but without success.