If your event is general admission (i.e. unreserved) you do not need to create a seating plan.
When creating a new event:
- In the "Ticket Allocation" column, select the option "Tickets are allocated from a general admission quota".
- In the "Section" column, click to "add new section", provide a name for the section (which could be 'Unreserved') and state the capacity.
- Continue creating your event.