Cut 12-inch hardboard into strips that are 6 inches in width, using a circular saw. Set them in your sidewalk area.
Hammer stakes into the ground along the sidewalk area, and attach the boards to the stakes to create a guide for the sidewalk. Screw a wood block into the joints between the boards, using drywall screws.
Dig between the board guides down to a depth of 6 inches.
Pack down the soil of the exposed area, using a tamper.
Spread a 4-inch layer of gravel along the tamped soil, using a rake.
Cut wire mesh so it is 3 inches shorter on each side than the width of the sidewalk area. Tie the pieces of mesh together, using wire and a pair of pliers.
Break open a bag of concrete into a wheelbarrow and pour the cement mixture on one side. Add the recommended amount of water indicated on the concrete packaging to the other end of the wheelbarrow. Mix the water and concrete together, using a shovel, until the concrete has a thick consistency without lumps. If you have a large sidewalk project, you may wish to consider contacting a concrete supplier and having the mixed concrete delivered directly to the job site.
Pour concrete into the forms. Spread it using a steel rake.
Level the concrete by pulling a 2-inch by 4-inch board along the surface until it is smooth.
Float the surface of the concrete with a bull float, pushing the float over the concrete, lifting up at the end and starting again, overlapping the first pass. Allow the concrete to bleed water onto the surface before continuing.
Smooth the surface with a magnesium float, using sweeping motions.
Separate the concrete from the boards, using a trowel edger and sliding the blade between the concrete and the boards.
Cover the sidewalk slab with 4 mm sheeting for approximately three days so the concrete dries evenly.