Topsoil can be used to fill low areas of lawn to make the yard level, and it can be used to top-dress bare spots. Fill a low area of grass by adding a 2-inch-thick layer of topsoil on top of it and leveling the topsoil with a shovel. The grass will grow through the new topsoil.
Topsoil can also be used to make a garden by spreading a 2-inch-thick layer of it onto a selected area then mixing it thoroughly with the existing soil to a depth of about 4 inches. Because there may be a big difference between topsoil and your garden soil, mixing it with the top 4 inches of your soil creates a transition layer that prevents drainage problems between the two soil types. After the soils are thoroughly mixed, add topsoil on top of their layer to make the garden the desired depth. Using a topsoil that has had fertilizer and organic matter added leads to the best results in plants.