Since the island of Korcula is yet to build a small airport, coming to Korcula is via two "nearest" airports - Dubrovnik ( 3 hours away ) and Split ( 3 - 4 hours). From both airports there would be a bus taking you to the town of Split or Dubrovnik where you would have a connecting bus to Korcula or if you wish to enjoy a tranquil scenery and travel in relaxed manner, you may want to take a ferry from the local harbor.
All the details will be worked out on time. No need to worry.