Zadar airport has one very small terminal where it is impossible to get lost. From the entrance of the building to the plane you walk barely 70 meters. Expect a shortage of seats in the summer season.
Departure counters are in the main part of the terminal when viewed from the outside on the right, while arrivals are in a smaller annex on the left.
A map of the terminal showing security and passport control, counters and shops can be found on the airport website.