@zboblamont I want to use Mysensors to add more information to my domoticz. And I would like to start with a gas sensor.

Thank both of you for the quick reply. I am going to order new components ;)

Ok, first of all I am new to the MySensors. I have read a lot and decided to order some components from Ali. Thanks to the info on this site I was able to make a Serial gateway, which is connected to Domoticz. And now I want to add sensors. I bought a Pro Mini atmega168 3.3V 8M Compatible Nano Replace Atmega328 For Arduino. But I failed to find any instructions on how to connect/use this board. Is it because I am not looking right? Who can enlighten me? I have also bought a MQ-2 MQ2 Smoke Gas LPG Butane Hydrogen Gas Sensor Detector Module For Arduino. So lets just say I want to connect this sensor. Who can help me?