Lay the cedar post flat on a work surface with one 4-by-4-inch end facing you. Place a center finder on the end of the post and mark the center with a pencil.
Drill a 1/8-inch diameter hole into the center of the post to the depth of the length of the threaded screw on the decorative post cap using a drill equipped with a 1/8-inch drill bit.
Center the threaded screw end of the decorative post cap over the drilled hole and thread it into the post until the bottom of the cap is flush against the end of the post.
Position the wrought iron hook 12 inches down from the bottom edge of the post cap in the center of the 4-inch width of one 4-by-96-inch side of the post using a tape measure. Drive the screws included with the hook through the mounting holes in the hook into the post with a screw gun.
Select a place to mount the post on your deck or steps and place a deck post mount in the selected place. Drive the screws included with the post mount through the mounting holes into the wooden surface with a screw gun.
Place the bottom end of the wooden lamp post into the deck post mount. Drive the screws included with the deck post mount through the holes in the mount into the post with a screw gun to secure it in place.
Hang a tin candle lantern from the hook to complete the outdoor wooden lamp post.