Allow anyone to register, not just those you've added to the invitation list.
1 Select your event.
2 From the left-hand navigation, click Registration, then Registration Process.
3 If applicable, select a registration path.
4 Click Open Site Designer.
5 Click the Registration Page dropdown in the top-left of the canvas.
6 Click the User-added image icon to the right of the registration path.
7 Scroll down to the Privacy Settings section and set "Who can register for the event?" to Open to the public.
8 Click Apply.
9 Click Publish to make this available to invitees.
Regards,
Peter