From here you can see a list of guests that are recorded against this property. If you click on the edit icon, you'll be able to edit their details in a form.
You will also, under the More option, be able to view their invoices and if required delete that guest. The guests are listed in a table which can be sorted via various column. You don't need to add guests to the booking system before they can make bookings on your property. Any user who makes a booking is automatically added as a guest. If you receive a telephone booking you can use the add booking button and enter their details directly into the booking form, when you save the booking they'll be added as a new guest, and if you want to make a new booking for an existing guest, you will be able to choose their name from a dropdown in the booking form.
A filter is also available to filter guests that have active/past bookings or to see all guests from all properties that you have access to.