Mold grows in areas of lawns that receive too much water and not enough sunshine. The first step in repairing a lawn with moss is removing it. The second is to keep the mold from coming back. You can repair a lawn with a few basic procedures and manual labor. The amount of work required depends on the extent of the growth. Mold-killing products will do the job, but are usually not necessary if you repair the lawn correctly yourself.
Break up the mold as much as you can with a rake or other tool. Rake up the mold and deposit it into garbage bags.
Use a spade to dig up spots where mold has formed because it grows under the surface as well. Dig down a few inches from the outermost portions of the mold. Replace that dirt with dry soil.
Plant grass seed on the bare patch where you removed the mold.
Fertilize the lawn. Use a regular fertilization schedule. Fertilizing helps the grass to grow and prevents mold from reforming.
Water the patch only enough to allow the grass seed to grow. Don't over water the lawn. Water early in the day, never in the evening. Water won't evaporate as much overnight, creating conditions for mold to regrow.
Aerate the repaired lawn with an aerating tool. Aerating tools puncture the lawn with a series of small holes. This improves drainage and helps the fertilizer get into the soil.
Keep the area as dry as you can. Fully mow the grass often and rake the area clear of any leaves or grass clippings. Allow the area to receive as much sunlight as possible. Remove (or cut back) any trees limbs hanging over it. Make sure the repaired area is well drained. If necessary, regrade the lawn to stop water from collecting.
Keep a sharp eye on the lawn to see if any mold grows back. Immediately dig up any new mold using the procedures outlined here and reseed the area.