MACBOOK AIR STORAGE

Exactly what model do you have? To find the model identifier open System Profiler in the Utilities' folder. It's displayed in the panel on the right. You may also find the complete model information by selecting About This Mac from the Apple menu.

You can install a larger HDD or an SSD. OWC also sells an adapter that can be used to move the existing HDD to replace the optical drive to provide added storage to go with an SSD.