on the return page, you need to add the encrypted password return behavior which will look up the user record.
the fp_data string is created by first concatenating the fP_id and fb_email values, then encrypting that string based on the encryption type used.
the encrypted password return behavior looks up the user record based on the fp_id and fp_email variables. it then concatenates the ID and email columns into a string and encrypts it.
that encrypted string is compared against the fp_data string to make sure they match
in addition to the email password return behavior, you need to add an update form to change the password.
you need to add an update record behavior to update the password ion the database based on the fp_id querystring variable.
it would be a good idea to create the email password page using the wizard as a pint of reference before trying to create it manually.