How to measure H2S using Volleman PCS 10

Hello to everyone. I need help. I have Velleman PCS 10 4-CHANNEL RECORDER. Working perfectly recording and writing output in notepad on my PC. I am hoping to get result of percentage of H2S or Hydrogen sulfide in the air. I have no idea how to do it and if I have to use formulas to get result. If there is anyone who might help i would be grateful.