Buy bagged topsoil if you are spreading it in a flower bed, vegetable garden or other small space. Purchase loose topsoil if you are laying it in a larger area, such as an entire yard. If you purchase bulk topsoil, you will need a truck to take it home or you can arrange to have it delivered.
Remove all existing material from the top of the ground, such as mulch, gravel or grass. Scrape under the material with a flat-edged shovel and place it out of the way.
Spread the topsoil in large piles around the perimeter of the area you are working in. If you are laying it in a small area, one large pile will suffice. If you are laying it in an entire yard, create five to six piles.
Use a wide-toothed rake or a shovel to move the topsoil around the yard until it is in an even layer that is between 4 and 6 inches thick.
Insert a ruler all the way down into the layer of topsoil until it stops to ensure that it is between 4 and 6 inches thick. If needed, apply more topsoil and spread it out evenly.
Place a tiller at the edge of the topsoil and set the blade depth as deep as possible. Turn the tiller on and run it over the topsoil to mix it into the underlying soil.
Rake the top surface of the top soil with a leaf rake to smooth it out as evenly as possible.
Rent or purchase a lawn roller at a home improvement store and place the roller at one end of the area. Push the roller over the topsoil once to firm it up.