Car won't start

you have a bad starter relay or a bad wire going from ignition switch to s on starter solenoid check for juice

Well first of all what is the application? I would like to have year, make and model. There are any number of issues which could prevent the vehicle from starting, even with a new battery and starter. Generally speaking the signal for the starter to engage comes from the ignition cylinder (key) switch. If the starter relay/solenoid does not receive a pulse (signal) from the key ignition, the starter will not even attempt to engage, nothing will happen. (you might here a little click). If there is a signal from the key, then the relay/solenoid is your next item to inspect. You can by-pass the key, the relay, and even the solenoid (in most situations), with the starter installed (base is well grounded, main terminal is hot) by sending 12v power directly to the small terminal (signal lead). It should actuate the starter. (Now that works on Honda, and Toyota, etc.... but really it depends on the vehicle). Give me all the info...foreign or domestic...and I'm happy to give you my best response. Remember...never give up...never surrender!