NBAR2 support was only added in NFA 9.2, so you would have to be at the latest version in order to use it.
The full NFA 9.2 bookshelf can be found here .
As Charles mentioned the Admin guide discusses creating NBAR2 application definitions, also it discusses importing the pre defined NBAR2 applications that are provided in a csv file when you install NFA 9.2.
The Operator Guide, also found in the NFA 9.2 bookshelf, discusses which reports will actually show this data, and right now that is only in the Flow Forensics report titled "Conversation Sessions (NBAR2) Report".
You should also note that we currently only support NBAR2 traffic with an EngineID of 13, this can be checked by running a PCAP on the Harvester and decoding the flow as 'CFLOW'. If you need help with decoding NetFlow using Wireshark check out this doc.