Step 1: Buy a RC airplane and learn to fly it well enough so that you don't crash. I would recommend a hobbyzone super cub. You don't want to destroy your creation as soon as you launch it.
Step 2: Build your own RC airplane from foam (see RC groups "foamies scratchbuilt" thread). It will teach you the principles of model flight and generic construction help.
Step 3: Scratchbuild another plane, this time with your retractable wings.