Flights to Zagreb, Croatia, check on the web sites of airline companies:
http://www.croatiaairlines.com/
http://www.easyjet.com
http://www.germanwings.com

Airport Split – Split
The transportation options from Airport Split to Split you can check here:
http://www.splitairport.info/split-airport-bus-timetable.html
http://www.split-airport.hr/index.php?option=com_content&view=article&id=185&Itemid=176&lang=en  

From Split to Brač, check the schedule of ferry lines on:
http://www.jadrolinija.hr/

Transportation from ferry port in Supetar to Postira (Hotel Pastura)
We kindly ask participants to plan their ferry line according to the bus timetable on these pages:
http://www.selca.hr/pdf/autobus-vozni-red.pdf
http://www.putovnica.net/prijevoz/autobus-supetar-postira-pucisca-bol-autotrans
Also, taxis are available in Supetar, so you can use them but at your own expense.