Purchase a gazebo kit form an online retailer or brick-and-mortar retail store. The kit includes fasteners and bolts needed to assemble the gazebo and have the largest pieces, like the roof and floor panels, preassembled.
Build a foundation for the gazebo. You can construct piers for the gazebo by digging holes in the ground and filling them with concrete or by building a concrete slab for the gazebo to sit upon.
Place the floor panels on the ground face-down. Assemble the floor and connect the different panels with the provided hardware.
Flip the floor over and move it onto the foundation.
Slide the roof support beams into place in the floor but do not fasten them to the floor.
Slide a wall panel into place between two of the roof supports and screw it into place. Repeat this until all of the wall panels have been installed.
Screw the roof support beams to the gazebo floor.
Place the roof trusses into position on top of the support beams and connect them where they meet in the center and connect to the roof support beams.
Place the roof panels onto the trusses and attach them with screws.
Screw the screens to the gazebo walls.