Lots of ways to do this. This is an excellent site.

Here is a link that might be useful: UC IPM site

Many "weeds" indicate a soil related problem, pH, nutrients, lack of organic matter, etc. so the first thing to do is contact your state universities USDA Cooperative Extension Service county office, or your local AgCanada office, to find out about having a good, reliable soil test done to find out what your soils pH is and what you might need do to correct any problem, and also to know about the macro nutrients in the soil. Then you can gid in with these simple soil tests,
1) Structure. From that soil sample put enough of the rest to make a 4 inch level in a clear 1 quart jar, with a tight fitting lid. Fill that jar with water and replace the lid, tightly. Shake the jar vigorously and then let it stand for 24 hours. Your soil will settle out according to soil particle size and weight. A good loam will have about 1-3/4 inch (about 45%) of sand on the bottom. about 1 inch (about 25%) of silt next, about 1 inch (25%) of clay above that, and about 1/4 inch (about 5%) of organic matter on the top.

2) Drainage. Dig a hole 1 foot square and 1 foot deep and fill that with water. After that water drains away refill the hole with more water and time how long it takes that to drain away. Anything less than 2 hours and your soil drains too quickly and needs more organic matter to slow that drainage down. Anything over 6 hours and the soil drains too slowly and needs lots of organic matter to speed it up.

3) Tilth. Take a handful of your slightly damp soil and squeeze it tightly. When the pressure is released the soil should hold together in that clump, but when poked with a finger that clump should fall apart.

4) Smell. What does your soil smell like? A pleasant, rich earthy odor? Putrid, offensive, repugnant odor? The more organic matter in your soil the more active the soil bacteria will be and the nicer you soil will smell.

5) Life. How many earthworms per shovel full were there? 5 or more indicates a pretty healthy soil. Fewer than 5, according to the Natural Resources Conservation Service, indicates a soil that is not healthy.

to learn more about your soil and what else you need do to make that soil into a good, healthy soil that will grow strong and healthy plants.
Then learn about the appropriate grasses for your area and the best time to seed, or maybe sod, that yard, But get your soil fixed first.

Firstly, fabulous advice from Kimmsr. It's always all about the soil when it comes down to it.

The only thing I would add is my experience of new construction and soil prep.

Where I live, a builder in a new sub-division will tyically remove any huge items of debris from the building site, but leave "everything" else. On top of this they will cover the surface with a scant 4" layer of top soil. The topsoil they cover it with is likely the original topsoil that was scraped off the area prior to the new subdivision being started. It is probably not screened in any way.

Quality of delivered topsoil comes from the degree to which it has been screened. The most expensive may have been screened through a quarter inch screen, the cheapest will not have been screened at all.

My usual advice to new home owners is not to accept the builders top soil. If it's already in place, more often than not I advise that they haul it out along with a further 8 inches of subsoil and bring in the most expensive topsoil they can afford. Even then it is not guaranteed to be weed free, and nor should it. Weeds play an important part in stablising new soil.

The most important thing for you to do before you do anything else is to identify the weeds that are growing there, and deal with them appropriately. This is expecially important if you have stands of aggressive perenial weeds such as thistle or quack grass. It is imperative you rid yourself of any noxious or nuisance weeds prior to doing anything else.

Also establish just how much top soil you have. I always recommend a depth of a minimum 12". 18" is better, especially if you want to plant trees. This much top soil will provide you with years of sustainable growth.

Hi. I bought a wooded lot 2 years ago and by the time I got to the grass issue it was all weeds like yours. I was on a very low budget so I pulled every weed by hand. Hired a company to spread quality black top soil (about 3-4") and immediately hydro seeded. The 1st year I had some quack grass but this year the lawn has snuffed it out and I have to say, best lawn in the neighborhood :o)

My Mom had this same problem when she got her new manufactured home. There were weeds everywhere! I recognize some of them in your picture. I think a lot of them were brought in by the construction equipment.

My Mom did not want to spray the weeds, so she started by watering the front area. She did about a quarter at a time. Once the soil was nice and wet, she pulled the weeds out with her garden fork, and put in grass seed. It took longer to do it this way, so that may not work for you, but she now has a lovely yard with lots of flowers. She's an avid flower and vegetable gardener, so that's one reason she didn't want to use poison on her yard.

Follow Kimmsr's advice and find out what kind of soil you have and get a soil test. It will benefit you highly in the future to tailor your amendments and activities to match the needs of the soil. As to your current problem, however, bare ground begets weeds. It won't stay bare, and a fine bluegrass lawn won't grow from nothing--it needs to be seeded, the weed seeds are there, so they grow.

However, for what you are looking at currently, go back after those weeds with roundup. Mix 1 1/2c. of the concentrated rountup (>40% active ingredient) in a 3 gallon sprayer, add a pinch (1/4 tsp) of surfactant (dish soap or laundry detergent), and about a quarter cup of nitrogen (water soluble plant foot with a good nitrogen content will work), then spray the weeds. They don't need to be wetted to the point of runoff, but just get good coverage. Wait about a week, then mow/cut the weeds off to clean up the yard. At that point, they will look sick and be dying down. Once they are mowed and the yard cleaned up, then you can get started on preparing to plant grass and set up flower beds and landscaping. Roundup is very rapidly inactivated when it hits the soil, so there will be no residual to damage anything you plant later, even if you mulch the weeds and work them into the soil.

From the appearance of the weeds, your soil is reasonably decent and can be used as is, or you can modify it before planting with organic matter or compost, however I doubt you will need to do any major soil renovation.