If CIS has forwarded the Notice of Approval of your wife's petition to the National Visa Center, the next step in the process is likely that NVC will be sending you some forms and information with respect to filing the application for immigrant visa and affidavit of support for which, you must first make the payment. Subsequently, you will need to provide all the necessary documents that will be sent to the US embassy in your wife's country for scheduling her immigrant visa interview.
Answered on Dec 19th, 2013 at 7:07 AM