First thing you need to do is to talk to your Ag Agent. They will give you advice on what to do and when to do it. Weeds are funny things. Spray them at the wrong time, and you just wasted your money. Time it right, and the results can be amazing!!!!
I was told to plan on it taking five years to get a pasture in really good shape. First you need to do a soil analysis to find out what your soil lacks. They will want to know what you will be growing on that dirt, and it's purpose. Grass can be for grazing or haying or just to look pretty. Different types of grass do better in differnt areas. Are you sure you have the best grass for your soil and climate?
Identifying the weeds is extremly important. You want to buy a chemical that will target those weeds, but not hurt your grass. You also need to know what time of the year the chemical works the best on the weed.
Every year, you will get a certain percentage of the weeds killed, and the soil will be a little better. First year, the results can be pretty impressive.
Good luck,
Eddie
Then you should identivy what weeds are