Ciao Thomas,
.... always from a beginner .... the temperature sensor has some characteristic, the relation between Volt and T. As far as I know,is generally 0,01 V = 1 kelvin degree and celsius = kelvin -273.
.... this could be a start ... it's important to understand which sensor you use because not all the sensor give the same value ... sorry if I'm obvious or wrong, as I said ... absolute beginner 