if you have connected it up properly it could be just that your battery is completely flat and that when you hook up the charger some relays are getting power and making the clicking noise
Charge or replace the battery.
I would suspect the battery has been discharged, is defective, or you have loose or corroded battery terminals. Remove and clean the terminals and if that does not solve the problem charge the battery with a battery charger. If it will not take a charge then replace the battery.
Does the engine turn over and then make the clicking noise while trying to start, or does it not do anything but make the clicking noise when you turn the key. If its not turning over at all then it might be a battery problem, Try cleaning the battery terminals, and/or charge the battery, Could also be the starter solenoid, but start with the battery first.
When the battery does not have enough voltage to turn the starter over it will sometimes make a clicking noise.
A loud fast clicking noise is usually indicative of a low battery or a loose cable.
If just clicking and not starting, most likely a dead battery.
The Battery is shot and you need to replace it.
Maybe flat battery?
dead battery or bad starter (with the clicking, I'm 95% sure its the battery)
dead battery
The starter or battery cables/terminals are corrode.
Low battery voltage .?