Take the base board from the toolbox kit. Stand this up on your bench. Take the front wall board and hammer 3 nails through it into your base board. Make sure the nails are evenly spaced. Do the same for the back wall.
Take the side wall boards and place in between your front and back boards. Hammer 3 nails into each side.
Nail your roof boards to the front and back walls. There will be overhang at the front.
Hammer your dowel into the pre-drilled hole below the entry point.
Use a hand plane around the edges of the birdhouse to create an arris.
Sand the birdhouse down using your 80 grit sand paper making sure you take off all the sharp edges.