When repairing a section of your lawn whose grass has died or suffered damage, your options are to either use sod or grow new grass from seed. Although sod offers convenience and instantaneous results, sewing your own seeds is far less expensive and much easier than you might think.
The first step is to choose the right kind of grass. Cooler climates enjoy the best results with fine fescues, Kentucky bluegrass, or perennial rye grass, while the weather and soil in the South and Southwest are hospitable to warm-season grasses such as Bermuda or Buffalo. If you're in a more temperate climate, sow the seeds in fall; plant them in late spring if the area is warm.
Once you've made your selection, cultivate the soil by working it deeply with compost or other organic matter. With either a spreader or your hands, sow the seeds without making them too dense in the soil. If too many seeds fall in too small an area, there will be unhealthy competition for available nutrients. After sowing, cover the seeds with a light layer of weed-free straw or salt hay, and protect the area from being trod upon by using stakes and twine to mark out the perimeter. Be sure to keep the seeds well watered, and after the grass has begun to sprout, you can remove the salt hay.