How to "wire" a new tachometer to the alternator

[bigoledave]

Greetings,

I purchased this tachometer and have it mounted..( looks awesome!).

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

In the instruction sheet, they show one wire going to the "W" terminal
on your alternator.. This method I now hear is not as good as one which
connects to the coil. So be it...I want to get this one operable and
"programmed " to read the correct RPM.

I am at a loss as to where this "W" connection is made on (or in?) my
alternator....any help is most appreciated.

Cheers!