I don't think there are any public buses direct from the airport. You would have to go back into Antalya town on the bus - to the bus depot - & then out again to Side. Hotels often arrange pickups - at a charge - email your hotel & ask them. Mostly if you are not with a travel company you organise yourself a private transfer. If you google Antalya airport to Side there are a lot of companies offering taxi or mini bus transfers. Taxi is approx �40 one way to Side from the airport - for up to 4 people.