After Green Card Interview When U Get Welcome Letter I Have My Green Card Interview (diveristy Visa) In The Embassy Of My Country After 2 Weeks. I Need Help?

I have my Green card Interview (diveristy visa) in the embassy of my country after 2 weeks. I need help? - after green card interview when u get welcome letter

I want to know what we prepare in the interview and what questions should I do. Is there a FAQ, is what I read syudy, or the preparation (eg, why here?)
So you very much for your help thank