Get rid of the sod covering the area you plan to plant. If you want quick results, you can dig it out, but it’s easier to smother it with newspaper. A layer of five sheets is usually thick enough; double that if your lawn is Bermudagrass or St. Augustine grass. Spread a 3-inch layer of compost (or combination of potting soil and topsoil) on the newspaper and wait. It’ll take about four months for the compost and paper to decompose.
If you don’t want to wait or if the area is covered with weeds such as creeping Charlie (Glechoma hederacea), you’re better off digging the sod out.