how to fit tachometer , where on alternator

it dont hook to alt,it hooks to coil pak that fires the engine.

please explain how .it is my first DIESEL ,DI

Their is a electeral box on drivers side of engine,has wires running out of it,use a test light to get power to tack,white wire on tack is a light for it .black is ground.you may have to test light several wires to get right one for the tack,each one you find hot hook tack hot wire to it crank do this until you find the right wire.they all in that 1 box.