Set the 1x6 board on edge. Position the 1x8 board on top of it so its edge is flush with the side of the 1x6 and the ends of the boards are flush. The 1x8 will function as the shelf, and the 1x6 will be under the shelf and mounted against the wall.
Drill six 3/32-inch pilot holes through the 1x8 and into the edge of the 1x6. Space the holes 11 inches apart. Drill a 3/8-inch hole 1/4-inch deep into the top of each pilot hole to hide the screw heads, and screw the boards together using 2 1/2-inch screws.
Sand the boards using first the medium-grit, then the fine-grit sandpaper. Wipe the boards down with the tack cloth and apply your wood stain. Let the rack dry according to instructions.
Screw the six coat hooks to the 6-inch-wide board so they're underneath the shelf. Space them 11 inches apart. The two outside hooks should be flush with the ends of the boards.
Locate four studs in the wall where you wish to mount your snowmobile gear rack. Position the rack against the wall so the shelf is on top and use your level to ensure it is horizontal. Screw through the rack using your 4-inch screws so two screws enters each stud.