Tachometer Help

I have a 1998 Mirgae LS, im trying to wiring the tach up but I don't know where the green signal wire goes? I cant find the signal wire....:banghead:

if you follow the wiring harness at the rear of the engine compartment about in midel you will find a( white wire with a blue connector ) on it nothing plugged in you can get a signal from here to your tac. green wire50100