That click, click, click that you hear is probably the starter solenoid. You can have someone try to start the engine and you get next to the starter and you should hear it real good.
It could be that your solenoid contacts are worn. Try this, get a rubber mallet or hammer and hit the starter a couple of good blows. Then try to start and see what happens. If it starts, you need to remove it and have it checked out.
The hammer hits may force the contacts to work or correct any starter motor issues that may be present.
The fact that you hear the clicks means that you are getting electrics to the solenoid. I would try this before spending money on parts or mechanics.
If this is not the issue then there are a couple of tests you can do to try to identify the problem.