How can I do a test (fake) registration, without being active? I want to see how that works.
First activate a session (semester) under Setup/Sessions, and ensure at least one of the classes in that session is activated (under Classes)
Go to your public site and find the class and click on register
Follow the new family wizard through (don't use your business email - to avoid confusion), and when you get to the payment page, just say you are paying cash.
Check everything in your admin system looks OK
Go to the class enrollment page in admin (Classes and click on the enrollment number "1/0"), select the checkbox next to the dummy student and click "remove" at the bottom. The enrollment will no longer affect your reports etc.