Plan the layout of the rebar by sketching out the sidewalk and the rebar on a piece of paper. You need to lay out the rebar needs in a grid, spaced evenly apart. The spacing depends on the weight carried by the concrete. You can space rebar in a driveway 18 inches apart, but in a deck or sidewalk, you can place it 24 inches apart.
Measure and cut the rebar to fit the dimensions of the sidewalk. Use a saw with a metal-cutting blade.
Lay the rebar into the trench where you are pouring the concrete for the sidewalk. Tie the different pieces of rebar together where they intersect with rebar tie wire.
Raise the rebar off of the ground so that it will sit in the center of the concrete. You can use small rocks or bricks, or rebar supports.