Tachometer Installation?

Hello,
My auto gauge tachometer just came in the mail, and i havent tried to install it yet. Just want to be sure of what im doing first.
There are 4 wires...

black (ground)
red(12V that is only on when ignition is on)
green(attaches to tachometer signal source)
yellow(12V battery(+)).

My main question is where is the tachometer signal source? Im running a completely stock D15B2 DPFI motor.

but also, what should i hook the red wire to too?

...my first attempt with anything that deals with wiring...please help.

thanks
-Cole

this should help u (http://www.wgn.net/~joe_r/tach/tachinst.html)

Tach is a solid blue wire coming off the distributor.

everything except the green wire runs to ur cd player