Cut a 14-inch section off your board. This section is your sliding latch. Cut two 3-inch sections from your board. Drill two pilot holes in each section -- in the center -- 1 inch apart from the other. Screw a small section to one end of your 1-foot section with 1-1/2 inch screws. Screw the second small piece onto the latch 4 inches from the first. Screw a leather strap to the second small section attached to the latch.
Place the level horizontal and span it between the door and the adjacent wall. Draw a line along the length of the level with your pencil. Make a mark on the wall 10 inches from the door. Make another on the door 4 inches from the wall. Cut six 3-inch pieces from your board. Give each piece two pilot holes.
Place a 3-inch section on the line, centered over the mark on your door, and drill it in. Place a section 2-1/8 inches over the first section and drill it into the wall. Place a section on the wall's line above your mark and drill it in. Place another section 2-1/8 inches above the third one you mounted and drill it in. Drill a section above the line of the wall next to the door frame and another 2-1/8 inches above it.
Hold your latch horizontal with the broadside vertical. Slide it in between the sections your drilled to the wall and the door with three sections above the latch and three below. Cut three 6-1/8 inch sections from your board. Drill two pilot holes in each; one hole, 1-inch from each end. Each of these sections covers the pairs of sections you drilled into the wall and door. Hold a section over the first pair of drilled sections and drill it into place. Do the same for your last two pairs of drilled sections. They span between the two sections, over the latch, holding it into place.