Install deck post anchors into your deck to form the four corners of a square by screwing them to the deck using wood screws. This will be the basis of your pergola supports.
Stand 4X4 timbers on their ends inside deck post anchors and screw them into the anchors to form four supports.
Switch drill bits from the Phillips head bit to the ½ drill bit and drill a ½-inch hole completely through the side of each landscaping timber. Each hole should be approximately 2 inches from the tip of the timber, and should orient exactly the same direction in each timber.
Drill corresponding holes in each end of four 2X4 boards. The holes should be in the center of the board, and spaced so that they each line up with the holes in the landscaping timbers.
Using a ladder, lift a board to the outside of two of the landscaping timbers on one side of your pergola structure. Lift a second board to the inside of the pergola. Bolt the boards into place at each end to form a beam using carriage bolts. Repeat the process on the other side of the pergola with a second set of boards and carriage bolts.
Switch your drill bit back to the Phillips head screw driver bit. Lift five 2X4 inch boards over the beams and space them evenly to form five rafters. Attach the rafters to the beams using hurricane clips and wood screws.
Lift the remaining boards to align crossways across the rafters and attach them with the remaining hurricane clips and wood screws.