Lay the two wood rails out side by side. Place a mark on one rail to indicate that it's the left ladder rail. Mark each rail at 12 inches, 28 inches, and 44 inches. With a 1/8-inch bit, drill a pilot hole through each rail at each marked point.
Cut the top and bottom rungs. The top rung must be 16 inches and the bottom rung must be 24 inches.
Place the wood rungs between the rails. Set the top and bottom rung in place. Use the pilot holes as placement guides. Measure the correct length for the middle rung. Cut the middle rung to fit.
Sand or file any excess wood to give a snug fit between the rungs and the rails. Continue to use the pilot holes as guides. Since this is a rustic ladder, you don't have to be precise. On the other hand, you don't want huge gaps between the rungs and the rails.
Drill a 1/8-inch hole in the ends of each of the rungs. Make the hole slightly deeper than the fastener goes.
Place the top rung between the rail at the appropriate mark. Nail in place on each end with a 16 penny nail. Continue by nailing the middle rung in place. Finally place the last rung, and nail that in place.
Round the top and bottom of each rail with sandpaper. If the rungs are rough, sand them so they can't snag your quilts.