To add a login and registration form to your online casino site, you'll need to create separate HTML files for each (login.html and register.html). You can use CAD GPT to generate the basic HTML forms for both. These forms will need to send data to server-side scripts, typically written in PHP, to handle the login and registration logic. Note that in the provided example, the forms are only for demonstration and do not include the server-side scripts, which you would need to create separately.