What part of the country do you live in ?

I'm in NJ.

Do you have pics?

Well you definitely have grass.

Unfortunately, it's crabgrass.

It depends on how much time and money you want to spend.

There are a number of threads here that detail exactly how to go about it. Right now is the perfect time to get started.

In short:

1. Kill everything with Round Up

2. Mow it at the mower's lowest setting

3. Apply more if weeds persist

4. Remove dead grass/weeds

5. Early September seed and fertilize

6. Water 10 minutes 3 times a day or so just to keep the seeds/soil moist

7. By mid September you should see grass

There are many more small details that are involved (what type of grass, full/partial sun, adding topsoil?) but this will at least give you an idea of what's involved.

Okay so there is a point to be made here. Even a crabgrass lawn can be made to look sort of decent. It will remain dense and yellowish green until it dies in the winter after the first frost. Even bermuda does that. The best thing to say about it is there are plenty of roots in the ground. That is great news, because your soil is benefiting from the dense canopy of grass and the roots in the ground.

As Joe mentioned there are other details. From your location you should have a sand soil. This is fine, but you're saying there are rocks. Are the rocks big enough to be a problem? Do you need to rake them out? If so then you could add a step 4-2 above and remove the rocks when you clear the dead grass out. Then as step 4-3 you could level the ground with a drag to get rid of high and low spots. Pulling a drag in sand is easy. I just built two walkways with a sand base - sand is great for leveling.

As for a grass choice, you have the basic three for your location. Those are TTTF (turf type tall fescue), Kentucky bluegrass, and rye. All three should remain green all year in your location, but KBG might go dormant/brown in a rough winter. KBG has the advantage of spreading to fill in thin spots, but it needs full sun. Fescue can tolerate shady areas. Rye needs full sun and does not spread. Those grasses which do not spread should be overseeded every fall to fill in any thin spots that might have developed.

All turf type lawns need to be watered regularly unless you get rain every week. Keep that in mind. If you are willing to do that then any of the grasses I mentioned should work. If you don't want to water every week, then you might benefit from a mix of prairie grasses that can fill in and remain green without regular watering. There are probably some wheatgrass varieties that grow well in your neighborhood.

Round up is not that toxic...….unless your eating a bunch of it. Keep them off until it dry's, and you should be good.