Put a volt meter or test light on the positive terminal of the starter.  If
you get 12 volts or the test light illuminates, then you have power to the
starter and the relay is good.

Take a battery jumper cable and apply 12 volts to the starter and see if it
engages,  If it does, the starter and solenoid are good.  The solenoid is
part of the starter.  If it does not, then the starter is probably bad.  Be
sure to keep clear of the fan and fan belts.

Take a thinner wire and apply 12 volts to the control side of the relay see
if the relay clicks.  If it does, it is good, if it does not, it is probably
bad.

Or, try a place like Sears.  Sometimes they do a basis starting system check
for free or very low cost.