Building the Side Supports
Set the four 10-foot 4-inch by 4-inch posts parallel to one another. Each side will use two of the beams.
Set the four 48-inch 2-inch by 6-inch beams perpendicular to the posts. The bottom piece should be 3-1/2 feet from the bottom. Place the top beam level with the top of the posts. Screw the beams into position with 3-inch decking screws and a power screwdriver.
Space four of the 6-foot vertical cross-beams between both sides of the end pieces. Secure them onto the inside of the upper and lower cross-braces with 1-1/4-inch screws.
Building the Top
Secure the 8-foot cross-beams to the outside of the posts with the 3-inch decking screws, spacing them with 1 foot at each end.
Space the rest of the 6-foot vertical cross-beams between the ends of the top cross-beams and secure them with the 1-1/4-inch screws.
Place the corner braces onto the four upper corners.
Finishing and Installing
Paint the entire arbor with your desired stain. Leave the stain on for 15 minutes and then buff it off with a clean rag. Leave it to dry for the manufacturer's instructed time.
Apply wood sealant and leave it to dry for the manufacturer's recommended time.
Dig the posts 3 feet deep with a post digger and place the posts into the ground.
Check to make sure the arbor is level on both the top and sides and adjust the holes accordingly.
Backfill the holes to secure the arbor in place.