How can I tell if my starter is bad? Tried to jump, because I thought it was my battery. Didn't work. Only hear click, click, when I try to start. Gave no warning.

It sounds that your solinoid is moving the mechanical part of the starter motor but is either not going in the ring gear deep enough or to make contact with the connections in the rear of the solinoid or your solinoid points on the inside are burned out or your earth cables to your engine might have a high resistance due to corroded connections or paint between the eye terminals and the engine block or battery.

It may be the solenoid is bad but you can have the starter tested at most auto parts shops