If you have a large area that you want to make sure is filled in with grass, there are various ways that you can do it.
One thing that you can do is to use sod. Sod is basically pre-grown grass. The way that it works is that there are large farms where huge fields of grass are grown. When the grass is ready, it gets harvested by harvesters that will cut strips of grass and that will run strips under the grass and under a small amount of soil. That way the strips will have grass on top and roots on the bottom. That will let the grass continue to live and be able to root in the ground when it gets placed in your yard.
Another option is to manually seed the area. The way that this works is you somehow spread the seed by hand. You can do this by using a seed broadcaster, which is a tool that you fill with the grass seed and it spreads out the seed. These can be tools that you hold in your hand and use to spread the seed, and there are also broadcast spreaders that you can push so that you can use more seed to cover a larger area without having to keep stopping and refilling the spreader. The problem with doing this is that it can be a lot of work and take a lot of time. You can also end up with an uneven spread. You are also going to have to go over the area and protect it with something like straw.
Hydroseeding is going to be another really good option out there. The way that this works is that you hire a company that will come out and do this for you. They will come out with a tank truck that is filled with a slurry of seeds, mulch, and dye. They will use a hose and spray that slurry around on the area that needs to be seeded. The dye will make sure that the people doing the seeding don't miss any space. The fact that the slurry contains a mulch means that straw or some other covering doesn't need to be used since the mulch will protect the seeds.
If you have a space that needs to be filled in with grass, there are different ways that you can do it.
For more information about hydroseeding, contact a company like Bark Blowers & Hydroseeding Inc.