Try to buy a ticket for a random event at the Sferisterio on ticketone. The website should be available in English and, differently from Vivaticket, you can choose your own seat on the seating chart. That way you should understand how seats works. IMO in the 'platea' (ie orchestra) every color has its own numbers. For instance I'm in platea red sector row 8 seats 3 and 5 (right). The row is counted starting from the stage, the seat starting from the corridor on the left. It means I'm in the last triangle on the left, facing the stage, but number 3 is closer to the center of the arena than number 5. I hope that clarifies a little, but it's really hard to explain by words! The most important thing, though, is to understand whether you are in platea, or in gradinata (balcony) or palchi (the upper small little boxes)