In your picture above of the starter RELAY, the larger terminal on the right has the smaller red wire that runs down to starter solenoid, on the starter motor
The small terminal at the top, has the wire that comes from ignition switch, it has 12volts when key is turned to START
When the smaller terminal wire has 12v this RELAY Closes, and sends 12v from larger left terminal to larger right terminal and that activates the starter solenoid on the starter motor
The starter RELAY needs a GOOD ground, the screws that are holding it to inner fender are the grounds, and they look pretty rusty, pull one screw out and clean it, so its bare metal where it holds down/touches the Relay base
Then MAKE SURE trans is in Neutral or PARK
Turn key off
Use a short jumper wire and touch it between the 2 larger terminals on the starter relay, starter should activate IF......battery cables are OK, can handle the AMPS
Try it a few times
If no 'click, click, click' then battery cables are OK(and so is starter motor)
If it does 'click, click, click' then battery cables ARE the problem(or starter motor is)
If it doesn't 'click, click, click', then turn on key, and try starting with key(with NEW ground for Relay)
If it does the 'click, click, click' then New Relay is either not grounded or its bad
You can test the small terminal wire with volt meter, unplug it, hook up volt meter and turn key to START(clutch pedal DOWN if manual trans), should see steady 12.3volts or what ever battery reads now, if its under 9volts then this wire is corroded somewhare