What docs for fingerprints and how it will be at the Uscis office?

[GC_Europe]

I have an appointment for fingerprints tomorrow and I would like to ask you what documents should I bring.....and how is going to be there..is it going to be an interview...do they ask you something...how should I get ready for this biometrics?..do they need to take a picture of you?

Thanks in advance..I would really appreciate this!