It's hard to get excited about installing a throttle cable, but without it, you couldn't control the speed of your motor. The throttle control cable runs from the remote throttle lever on your dash to the throttle arm on the carburettor of your outboard motor. When you need to install a throttle cable in your outboard, the real work of installation is done at the motor rather than at the remote throttle lever, where the connection is nothing more than placing the cable under or around a screw.
Attach the throttle cable, not the cable casing guide, but the cable itself, to the throttle arm on the bottom of the throttle lever and tighten the locknut snugly with a small adjustable wrench. Visually verify that the fast idle lever is in the run position -- down instead of up.
Tell your assistant to rotate the propeller shaft of the outboard slowly, by hand. As your assistant does so, shift the gear lever from neutral to forward then half the distance back toward neutral. Do not shift fully into neutral. This positions the control handle for the adjustment.
Move to the carburettor and move the engine's throttle lever so the spark lever stop screw, the screw next to the throttle arm where you attached the cable, is against its stop. Attach the throttle cable casing guide to the hole at bottom corner of the throttle lever by inserting the pin through the clevis on the casing and setting the cottar pin through the end of the clevis, using a pair of needle nose pliers so the cottar pin is installed parallel to the raised rib on the corner where you attach the cable guide. Bend the ends of the cottar pin apart.
Set the cable drum in place and thread the cable retainer screw through it, without tightening it. Start the motor and ensure the idle speed is correct for your motor -- the correct idle speed can be found in your motor operator's guide -- and visually verify that the idle speed screw is against its stop. Move the throttle cable, if necessary to ensure the idle speed screw remains on its stop while the motor is idling. Once the throttle cable adjustment is correct, tighten the cable retainer screw snugly with a screwdriver.
Remove the two screws that hold the remote throttle in place. Remove the cover screws, usually three, to open the unit. Install the throttle cable trunnion in the housing pocket. Pull the cable tight and secure it to the throttle lever using the throttle control clevis and the throttle control pin. Tighten the cable trunnion with the adjustable wrench to secure the cable.