Be careful. The Diversity Visa Lottery is held each year (October - December?) and there are a lot of scams. It's free to enter, so you don't have to pay anyone.
Keep in mind that if you are undocumented, you won't be eligible to adjust status in the U.S. if you were to win. If you are covered under 245i, you might or might not be able to adjust... I can't find a definite answer (but I read that it doesn't hurt to try). After all that, even if you win, you are not guaranteed a visa.