Question
My family's backyard is not yet finish. There is concrete but no grass jus dirt, well weeds. What is the quickest and best way to kill the weeds. That way we can start to lay the grass. The weeds is a few different kinds. I have no real knowledge for plants. Thanks for your time  

Answer
Hi Daiel;
First make sure you have good, loose soil.
Buildres usually bring a little bit of top soil, but they only put about 1 or 2 inches of it down, and there may be hard clay underneath, in which case you are going to just buy years of trying to amend this poor soil, and battling to get a good lawn.
You want loose soil at least 6 inches down.
If there is too much sand, it will not hold water long enough for the grass and plants to benefit from it. If there is too much clay, that is too tight for water and nutrients to penetrate.
Also, weeds hate rich soil. They thrive in poor soil, so make rich soil, and you won't have to bither with the weeds.
Fertilizers don't enrich soil. They just feed the vegetation, wear out and have to be replaced. They DO kill beneficial micreobes that DO enrigh the soil though.
If you have too muc sand in your soil, you will need to buy some good loam to till in with it til it is the right looseness. If you have too c\much clayy, you will need to till in things to loosen it.
Insecticides kill bad insects, and beneficial insects as well. Make a safe enviornment for natural predators, and they will kep away the bad insects better than the poison insecticieds will.
If you live near a large nursery with a good supply of products, you should be able to get Landscaper's Mix, sometimes called Planyer's Mix.
If you live in Texas, I like Calloways Nursery. They are in all or most of the larger towns in Texas.
You can make your own mix.
This is what I use
To 1 bag peat moss, and 1 bag of humus, I put 3 or 4 bags of cedar bark mulch, dependng on how much I have to loosen up the soil.
Here, I have very hard clay soil, so it takes more bark mulch to the peat and humus.
I mix that with 1 part existing soil.
So you would make the mix, lay down 3 to 4 inches of it, and till to a depth of at least 6 to 8 inches.
That is some work, but in the long run it will save you many, many6 times the labor, and frustration.
After you till it all, seed or sod your lawn, put down sugar ( lain old sugar like you use in the kitchen), at the rate of 1 pound per 250 sq.ft. of lawn.
Water to a depth of at least 6 inches.
Follow the watering advice for the type of grass you are putting in.
Deep watering, to a depth of a least 6 inches, will encoupage a deep root system. That helps protect the grass from heat, cold and draught damage.
Shallow watering makes the roots come to the surface to get water. They suffer moe from heat and cold, die and lie on top of the ground, trapping other debris. That makes a layer of thatch, and that is a thick mat that will not allow water to penetrate. They everything dies, and you have to start over, or you have to dethatch.
I have a good, deep root system, so I never have thatch, and never have to dethatch.
NEVER SCALP a lwan. That is the worst thing you can do.
The sugar keeps the beneficial microbes that enrich the soil, alive, and they work round the clock, year in and year out, making your soil noce and rich.
I put sugar down in the spring and again in the fall.
That is all I do.
I let my lizards, toads and grass snakes kill the aphids, and other bad bugs.
I spray my rises and other shrubs when new growth starts in the spring, with baking soda disolved in water ( on top and underneath leaves and stems). Tht keeps away molds and fungus. I NEVER have any aphid damage on my roses, like I did when I used chemical fungicides.
I don't have grubs, army worms etc, like I did when I used chemicals. And my allergies and Asthma doesn't bother me nearly as much as they did when I used chemicals.
 Organics is more about what you DON'T do than what you do.
Read some of my other answers on organics.
Any time you have a question, feel free to write.
I love to share what I have learned about organics.
I like helping others get as much pleasure out of gardening as I do.
Charlotte