I searched all over about how to do this, and got tons of long, involved procedures, with strict quantities, testing soil, etc etc etc. Is it shade, sun, north, south facing, etc....?
I wasted days trying to figure it out. Took practically no time and effort, and within 2 weeks the new grass is thin and dark green, looks like it's been there forever.
You experts will laugh at this, but the first time it's always a guessing game whether to read the packages or who to listen to....
For the other dummies, this is what worked for me...
1. Get some of that sun & shade grass seed that is coated with something to help retain moisture. Also birds don't seem to eat the coated type.
2. Get some plain old garden soil containing mulch. Don't need fertilizer, additives or anything fancy for this.
3. If you don't know what the soil needs, just get some general purpose fertilizer 10-10-10. If the yard is not dark green, use high nitrogen like 24, with some sulfur and iron.
4. Rake up the dead grass and thatch in the bare spots and dump it.
5. Sprinkle the seed so that the seeds are about 1/4- to 3/4-inch apart. Just guess, it's not that important.some.
6. Sprinkle the garden soil over the seed by hand if you just a few spots. Just enough to cover the seeds. I used 4 cu ft and save a bunch of money by just covering the seed and not the whole yards.
7. Water it until soaked, but not enough to run off. Use fine spray to keep from splashing the seed around.
8. Water it several times a day to keep the top damp. Don't need to soak it again. For me in So Calif I had to water 2-3 times a day at first due to dry windy days. Don't let it dry out if you can help it. But if does, just go back to watering and it will be fine.
9. 3-5 days later, grass started to poke up. After a week it was an inch. 3 inches after 10 days and started to fill in between the blades. After 2 weeks it looked great.