Q: I have 2 gigs of memory and 8 gigs of storage why can't i download mavericks

Does your MacBook Air meet the other requirements?

To install Mavericks, you need one of these Macs:

iMac (Mid-2007 or later)

MacBook (13-inch Aluminum, Late 2008), (13-inch, Early 2009 or later)

MacBook Pro (13-inch, Mid-2009 or later),

MacBook Pro (15-inch or 17-inch, Mid/Late 2007 or later)

MacBook Air (Late 2008 or later)

Mac mini (Early 2009 or later)

Mac Pro (Early 2008 or later)

Xserve (Early 2009)

Your Mac also needs:

OS X Mountain Lion, Lion, or Snow Leopard v10.6.8 already installed

2 GB or more of memory

8 GB or more of available space

You don't have enough storage space for a start. What model Mac do you have?