why doesnt my car start?

i have a 97 pontiac gt and when you turn the key on all the light come on and then when you go the start is its like theres nothing there i replaced the starter and still the same thing and all the fusees are good. what can i cheack that might make it not start?

nss switch, transmission in gear, low battery,

what size engine so I can look up diagram for you?

the motor is a 2.4 liter

use dvom (digital volt ohm meter) red probe on the purple wire of the starter solenoid black on the good engine ground, tell someone to crank engine for you then tell me what your dvom read.