After you've cut the pressure treated
2x6 pieces, begin to connect them with deck screws
and a power drill
. Place two of the long pieces on end parallel to one another, and fit one of the 9" long pieces of stock between the two sides at each end. Drive two 2-1/2" deck screws through the sides into the end pieces as shown in the picture. Repeat with the other set of sides and end pieces for the second box.