I assum AN means App Notes. I had a look on the microchip website and i found a document that describes how to measure watts. It seemed to be what i wanted because it measured amps and volts to get watts but it either wasnt clear enough or i just dont get it.

What i understand now is that i need a device to measure volts/amps. That device sends an analogue signal to the PIC through an ADC pin. I also read that 2 volts has to be added to the analogue signal and it needs amplifying so the PIC can read it more accurately.

First thing, did i understand it correctly? Second thing, what is the component used for measuring amps?