DV winner processing is a not a complicated one, if you have all the necessary documents.
First you check your DV-2018 or DV-2019 results if you are selected in the draw,
There are 50,000 slots only available and nearly 100,000 winners will be selected to issue them.
So, not all the winners will be called for the interview.
Some time before your case number is called for the interview, the visas may get exhausted.
So still the selected winners luck is looming over there.
Now take a new American Visa photo for you.(If have dependants then take for them too)
Don't wear eye glasses, when taking photo.
Now it is time for you to fill your DS-260 online visa application form.
Get a printout of the final page after completing the application form.
Now it is your turn to look in the visa bulletin every month to see when your case number is becoming current.
Now you have two printouts with you and these two sheets should be produced to consular officer at the time of your interview.
Plenty websites are misleading you with the First Letter and 2NL - Second letter. But there is nothing like this from the State Department.
When you are selected as a winner you will be shown with a Winner Notification with a case number. (This is called by the DV marketers as "First Letter"). To check for the Interview notification you will need to feed your confirmation number and your personal details as like checking your selection results.
When you are scheduled with an interview you will check in the results checking website and will find the interview letter.
(This is called by the DV marketers as "Second Letter and as 2NL") This notification too should be printed out.