Fallen leaves make wonderful free compost. Composted leaves contain leaf mold, which has high amounts of calcium and magnesium, both important to healthy plant growth. Leaf mold also retains moisture that, when added to garden soil, helps young plants stay hydrated.
Determine where the compost bin will be built. Ideally, it will be on soil, in full or partial sun, and near the garden. The farther away the bin is from the garden bed, the more hauling that needs to be done. Measure out a 4' square in the ground and mark the corners.
With a circular saw, cut a point onto the ends of four 2" x 2" x 5' pieces of lumber. This will make it easier to drive the lumber into the ground. Use a hammer to drive one stake into each corner of the 4' square marked onto the ground. Drive each stake 12" into the ground, trying to keep each one straight and square to one other.
Use a staple gun to attach one end of a roll of 4'-tall chicken wire to one of the stakes. Secure with approximately 6 to 10 staples. Continue wrapping the chicken wire around all the stakes, securing to each one with multiple staples. Secure to original stake with staples to form a fully enclosed bin.
Use a lawnmower with bag attachment to collect fallen leaves. This breaks up the leaves and jumpstarts the decaying process. When the bag is full, simply empty it into the compost bin. If the leaves are very dry when placed into the bin, hose them down a bit to get them damp.
To speed up the composting process, add to the leaves a handful of lime and a handful blood meal. Turn the leaves with a pitch fork now and periodically throughout the season. If the compost pile starts to appear dry, spray it down with a garden hose and turn with pitch fork.