won a prize and win a free trip to Las Vegas - b2 visa

[ksc]

Hi,
We won a prize and free paid trip to Las Vegas, USA. We have all the records related to that prize achievement certificates and photos.
Along with sponsored trip I would like to visit other places also like LA, NY etc in USA. I applied for my family since our close relatives are there.
For family members applied as self sponsored though, I had the invitation letter from relatives to the family.

How should I be prepared for the interview and what all documents I should carry.

Interview at Hyderabad.

Thanks,

CSK