Use a garden tractor and a garden drag to level the ground where the shed will be located. Remove any large rocks or other debris from the area. The shed will be built with treated lumber for the floor joists so it isn't necessary to place any mositure barriers on the ground. However, if preferred, a large garden tarp can be laid across the location where the shed will set to provide a barrier between it and the ground.
Cut 4 floor joists from 2 by 6 treated lumber. Measure the length of joist to be 5 feet 8 inches. When the side beams are attached the overall size will be 6 feet by 6 feet. Using treated lumber helps protect the floor of the shed from rotting due to moisture coming up from the floor.
Attach the 6 foot 2 by 6 side beams to the floor joists with wood screws. The end joists should be flush with the end of the side beams. The remainder floor joists should be secured to the side beams 2 feet apart. Use a carpenter square to ensure the shed foundation is built square and straight.
Place a 3-foot level across the tops of the floor joists to check for the levelness of the floor. If a high point in the floor is located use a wood chisel to cut the joist down until it is level.
Cover the floor with 3/4-inch plywood. The plywood should be secured to the floor with wood screws inserted through the plywood into the floor joists.
Position 2 pieces of 6-foot framing lumber on a level surface. The boards should be parallel to each other with a 8-foot distance between them. This is the top and bottom of the wall. Place 8-foot long 2 by 4 wall studs between the top and bottom wall boards. There should be at least 3 studs per side, one on each end and one in the middle. Use a level to make sure the wall studs are straight and place it across the top of the wall to ensure the wall is standing straight. Secure the studs with wood screws. Repeat this process for 3 other walls.
Place a 6-foot piece of framing lumber on a level surface. Before attaching studs determine where the door to the shed will be. Mark the location of this 36-inch opening. Cut the opening from bottom piece of framing lumber. Attach 8-foot studs at the ends of the wall framing lumber and on either side of the door opening and use a level to ensure the door frame is straight. Cut a 36-inch piece of 2 by 4 and position it with a level to make sure the header is level. Secure with wood screws between the studs on either side of the door opening to provide a header for the pre-hung door. The header should be placed at the height of the pre-hung door.
Lift the wall frames into place on the floor of the shed and use a square to ensure the walls are square with each other and the floor of the shed. Secure the wall with wood screws into the shed floor and into the floor joists. Screw the studs at the corners together to provide stability.
Lift roof rafters into position and secure them to the wall frames one at a time. Place a 3-foot level on the cross beam of the rafter to check if it is level. If necessary place shims under the low side of the rafter to raise it enough to make it level. Position the rafters parallel with the door so that runoff from the roof won't land in front of the door. Use galvanized nails to secure the rafters.
Cover the roof with 1/2-inch plywood and secure it to the rafters with wood screws. Cover the plywood with tar paper and secure in place with staples and the staple gun. Lay shingles over the tar paper starting at the bottom of the shed and working up the top. Make sure that the shingles are staggered so that no seam of the shingles is directly on top of another seam. Secure the shingles with roofing nails. Place a roof cap across the ridge of the shed roof and secure with roofing nails.
Cover the exposed wall studs with cladding underlay. Secure the underlay with staples and the staple gun. Remember to cut the opening for the door out of the underlay and wrap the edges around the door frame.
Attach weather treated siding to the wall studs on top of the underlay. Secure the siding to the wall studs with galvanized nails. Measure and cut the opening for the door out of the siding.
Install the door and paint the shed if desired.