Apples are traditionally stored in cold storage so they remain in good condition, pick them before they are fully ripe.
On the racks you will need butcher paper (the non plastic filmed kind(it is brown not white)) lay a sheet of the paper on the rack and another sheet between every layer of apples.
Build a door that allows for ventilation, there also should be two vent pipes (like a good
root cellar) for air exchange.
Install a thermometer or have one sitting on the highest shelf to monitor the inside temp. it should be around 45-55 f. for best long term storage.
The cold will keep the Drosophila melanogaster (common fruit fly) from doing any damage.
Redhawk