Greetings Joy,
This is discussed in some detail in the Purview Users Guide, starting about page 35.
If you navigate to this link.
https://extranet.extremenetworks.com/downloads/Pages/NMS.aspx
Select Documentation -> Select Manuals and Release Notes -> Select Version 6.2 -> Select Purview Users Guide.
Search for Custom Fingerprint Examples.
Since it is pretty comprehensive, I won't try to guess what approach you would like to take. if you have a specific example you would like to cover, please post more detail on what your trying to capture. If it's secure information, then I would recommend opening up a case.
