mq135 for co2

Other Hardware Sensors
1

hello,

i want to use the mq135 for co2, but i dont understande what i have to do......
my english is not so good and iam new with arduino.....

i have connected the sensor on ma a0 and have a 10,4kohm resistor between ao and gnd.

what libary to i need to use and what sketch ?

for calibration i burn in the sensor an fresh air (390ppm) and read the resistanze of the senor out ?
but how can i do that ?

thank you and sorry for my english.

2

i only have found this:

but for the rzero the serial monitor only shows me "inf"