DV2015 is the first year they use the electronic DS260 form. This form will be processed by Kentucky Consular Service.
You can fill it out here: https://ceac.state.gov/ceac/
Here is a sample form: http://travel.state.gov/content/dam/visas/DS-260%20Exemplar.pdf
Try to submit your DS260 as soon as possible. Your interview will not be sooner when you filled it out earlier than others, but if you wait to long it can delay your interview, and you will maybe even miss your chance.
When you submit the DS260 it will take 1 to 2 months to process it. The only thing KCC does is check if everything is filled out, and seems ‘correct’ so no gaps or inconsistencies. That’s the only thing they do! They don’t check the content and if you are eligible for the visa, that is up to the consular officer at the time of the interview.
When you made a mistake you are able to request KCC to reopen your DS260 via e-mail. This will NOT affect your chances, but it takes a few weeks for them to reopen it, and after you submit it again, it has to be processed again. So always try to keep 2 months between your date of interview and submit and/or resubmitting your DS260.
When you want to re-open your DS-260 (because, for example, you made a mistake, or something changed in your situation) you have to e-mail them and ask them to unlock your form. E-mail to email@example.com and put your CN in the subject line. Then, in the body of your e-mail, put your CN, full name and D.O.B., continue with your question or request.