Did you try the search function? Searching for " sonoff tasmota mqtt files" I get this thread.
Your description is unclear, what mqtt broker did you install. You need EITHER the embedded mqtt broker OR mosquitto!
Additionally you need a broker thing (which acts as bridge between the mqtt broker and openHAB). It sounds as if you migth have that already.
Once you have setup mqtt things and linked items ( either via file or via via PaperUI) they will show on PaperUI!