You must login to add your dealer details.
Edit this form at https://buyusedguns.com.au/wp-admin/admin.php?page=ninja-forms
It automatically adds the userID, so you can review the submission at https://buyusedguns.com.au/wp-admin/edit.php?post_status=all&post_type=nf_sub&form_id=3
You can then go to the user, and edit the field.
You would add the dealership number and also upgrade to dealer.
