According to Google it is an analog device with falling resistance with increasing concentration. Put it in a circuit with another resistor in series and connect the mid point to an analogue input. Depending on which side of the set up you connect to 5v and which side to 0v, you can get the input to read high numbers for increasing H2S or lower numbers.
As an aside, as h2s is do toxic, where are you getting the h2s from to play with your sensor?
As I recall a few 100 ppm is hazardous to Heath. Good thing your nose will detect a few ppm!