Rake the lawn to remove dead grass and roots. The pre-emergent should take care of weeds before they emerge, and is applied in the spring before temperatures reach into the 50s. Wait at least six to eight weeks before casting seeds to ensure there is no affect from the pesticide.
Look at the package of grass seed. It should indicate an overseeding quantity. Fill the garden spreader with half of the recommended amount for your type of seed.
Walk over the lawn with the spreader, moving back and forth in rows. Repeat with the other half of the seed, in rows at a perpendicular angle to the first.
Sprinkle 1/4-inch of topsoil over the lawn, letting it fall between the blades of grass and over the seeds.
Water the grass to soak it down to 2 inches deep. Continue to water every day until blades of grass grow, and then water twice a week to equal 1 inch of water per week.