Concentrate on getting the MQTT stuff working first; only then turn to openHAB.
Follow the instructions in the Tasmota documentation. In short:
- Enable MQTT
- Host: IP address of your computer that is running Mosquitto
- Client: unique name for your device - let’s use 4chPro2 for now
- Topic: 4chPro2
Leave everything else as default.
Now, using MQTT.fx, send an ON message to the following topic:
cmnd/4chPro2/POWER1
I think this should switch on the first relay. If that doesn’t work, using the Tasmota web interface to toggle the relay on and off, and then go into the Tasmota web interface Console and see what commands where sent.
Tasmota documentation. But that’s quite a list: just use the Tasmota web interface buttons first, and see what the result is on the Tasmota web interface Console.
I haven’t used it on Windows so can’t answer this myself, unfortunately. For me, there was no configuration required after setup.
Yes, it’s fine for both to be on the same machine. But again, concentrate on understanding and getting MQTT setup before moving to openHAB.