Thank you for buying Gwangi. We hope it will suits your needs!
If I understand well, you would like the user to complete his profile during the registration. To achieve that, you need to edit the registration form. The Register page cannot be edited directly. However, you can create new member profile field and choose to display them in the registration form.
For more about this, please read the following post: Modifying the Registration Form.
Also please sure that you either log out of your website or use the private navigation from your browser to view your changes you’ve made to this page.
Hope this will help you.