Spotlights draw a lot of amperage, which can be too much for a simple toggle switch to control. Wiring a relay in the circuit for the spotlights allows them to draw the full amount of power they need, and allows controlling them with a small low power switch.
Disconnect the negative cable at the vehicle battery.
Mount the relay using a self tapping screw in a protected location near the battery.
Install a solderless ring connector on one lead of the inline fuse holder and attach to the bolt on the positive battery terminal clamp.
Using a piece of 14 gauge primary wire and butt connectors, extend the other lead of the inline fuse holder as necessary to reach the relay.
Use a solderless female spade connector and attach the lead from the inline fuse holder to pin 87 on the relay.
Connect a lead from pin 87a to pin 86 using a short piece of 14 gauge primary wire with female solderless spade connectors.
Run a 14 gauge wire from pin 85 to the spotlights.
Install a toggle switch in a convenient location in the vehicle. You may have to drill a hole to mount the switch, or simply use a bracket and install it with self tapping screws.
Run a wire from pin 30 on the relay to either terminal on the toggle switch. Use solderless female spade connectors to connect both switch and relay.
Make a wire lead with a ring terminal on one end and a female spade connector on the other. Attach the spade terminal to the second switch terminal, and the ring terminal to a good ground under the dash, using a self tapping screw.
Reconnect the negative battery terminal clamp. Test your relay circuit by turning on the toggle switch. This grounds the coil in the relay, closing the contacts and switching on your spotlight.