If you initially set your event up as either general admission (Space) or allocated seating (Seat), you will have the option to change the event to table seating.
To do so:
From the Dashboard, under Manage events overview, click the name of your event
From the left menu, select Allocation, then Sections
Click Add New Section
Give the section a name eg. Tables, then click Next
In Allocation Type, select Tables, then enter in the Number of Tables you will have at your event and the Number of Seats at Each Table
Click Save
Locate the original section that was on your event, select it by placing a tick in the box to the left
Click Remove Section
If your event has already received bookings, you will not be able to remove the Section.
To manage this, you can either move the existing bookings to a new Section before deleting the original, or change the Section's status to Hidden to prevent it from appearing to customers during booking.