hooking up tach

My freind gave me his old autometer tach and i hooked it up and everything and works/looks great. my question is where do i hook up the white (shift light) wire?

a link to a tutorial on hooking up a tach would be nice too... i have been curious about this for a while

http://www.westworld.com/~joe_r/tach/tachinst.html You're Welcome.