That sensor is read using analogRead. So your existing code will work as is except that you'll need to change some of the text in the serial.print statements and you'll need to adjust the conversion factors to get to PPM. You can just print the raw values from the sensor to start with and verify that it changes when you blow on it.
The circuit is given on the page I linked earlier - you just need to choose the resistor required which is covered in the text on that page.
Don't forget that that type of sensor usually requires a 24 hour burn in period before you use it.