I'm using Visigo FBA pack for user's registration. but i need to add some more fields in that registration form . So is there any way we can achieve this . SQL server is used in back end for storing values
When I add extra fields, I usually add them to the user's SharePoint user profile - so they're available throughout SharePoint. But they can definitely be added directly to the membership database - look at using the profile provider to write custom fields to the membership database.
As for changing the code, I usually search for an existing field in the code (email). Then I just add the logic for loading, adding and updating the new fields wherever the email field is referenced.