Interfacing with MG811 CO2 sensor

Hello.. i'm really stuck in interfacing MG811 sensor with arduino..
first i tried simple method by taking analog output of sensor by command analogRead.. but the output is coming between 40 to 60 (almost), i don't find any relation between these values and PPM (parts per milion)..

can anybody basically guide me how to interface this sensor so that i can get the answer directly in PPM... I need a code hint and also the circuit!! I can't find tutorials..

Do you have JUST the module? Or do you have something like this?
http://sandboxelectronics.com/?product=mg-811-co2-gas-sensor-module