The big solenoid is realy easy. There are 2 big screws and 2 small. One big one gets power from the batt and the other goes to the fan. When its not switched the contacts between the two big lugs are open so no current goes through it. If you wanted the easiest set up possible you can make a jumper to go from the batt side of the solenoid to one of the small leads. Then run your solenoid ground wire to the temp sender and when the motor heats up it will close the contacts in the temp sensor and ground out the solenoid causing it to close the contacts and turning the fan on.
That's the easiest way. Only down side of this way is when ever your motor is over 180 degrees it will turn the fan off.. You go out for a drive and when you park the fan will run until the coolant in the head drops below 165.
The next easiest way to wire it is to find a 12v ignition hot wire and run that to one small lug in the solenoid the. Run the ground through the sender like above. Now it will shut off when your ignition off.
After that you can run either wire to a switch in the cab to allow you to turn it on and off as you wish.
There are some very cheap controllers and some very expensive.. You can make wiring a fan as expensive and difficult as you want. I like KISS.
If you need help let me know.. I can talk you through it.
88 YJ 35's 8.8 rear, family style roll bar, ax-15 external slave conversion, Custom double D fab dash 4" of lift taurus fan, Head light wiring upgrade, MSD 6al