The Congressionally mandated Diversity Immigrant Visa Program makes available 50,000 permanent resident visas annually, drawn by random selection among all entries, to persons who meet strict eligibility requirements from countries with low rates of immigration to the United States.DV Program (also called Green Card Lottery)
You can enter the lottery all by yourself and don't need a lawyer or agency to help you with this at all. There are many scams out there that charge a fee for doing something for you that you can do yourself without paying anything. Don't fall for this and do not pay any money to anybody for something that is free. Check out the sites I referred to and learn more about the Diversity Immigrant Program, also called Green Card Lottery, and what you have to do to enter it.
You have to make sure that you fill out the required forms properly or you will disqualify automatically.
The USAGC claims that about 30% of all applications get disqualified every year, because of errors made in the submit paperwork. If you have a problem with the forms and want to make sure that you get it right, then you might want to pay a service who is doing it for you and double checks, if you provided all necessary information.