I don't understand what a Web Reg Form Graphic URL is or how to add it?

Each Event Type allows you to add a graphic or image to the registration form associated with it. This graphic image must be entered as a URL. This offers you the opportunity to create and use special images and graphics for specific events. For example, you may have a special image that you use for birthday parties and a different image that you use for open houses.

In order for the image to be displayed on your event registration form, it needs to reside somewhere on the internet and have a URL (a web address that usually starts with https://). In many cases, you may already have the image somewhere on your website. If not, there are many cloud-based services that provide an instant URL when you upload the image to the service. For more on upload services, see this helpful internet blog article.