1. To add a new registration, you have to be first on your admin account.
2. Press on the Event tab ( ) from the left side of the page.
3. Then press on the List tab ( ) from below in order to see all events.
4. Then press on the registration form from the registration column on the right of the wanted event.
5. Here you will have to fill the required(*) fields in order to add at least a basic registration, filling the other fields will add more detail to your registration, but they are optional. After filling the fields, press on the Register button in order to register a pending invitation to a user for the event.