registering a product to download from the app store

Hello forums, I recently was given a macbook air, A1304. I have a problem on my hands. I have Mac OS X 10.6.8 and would like to upgrade to mavericks. Though, my apple product is not registered under my name. How can I register to download from the app store? Apple says theu are unable to register products right now. Is there another way to download the newest software?