Holy crap this page is doing stuff to my eyes.
http://azure.microsoft.com/en-us/services/documentdb/
Just try to read the text in the green area with the checkboxes next to it. Does the blue button seem to jump around under it as your eyes move?
umm http://azure.microsoft.com/en-us/services/documentdb/?
This is a JSON DB on Azure which you can use your student credit for... Why reinvent the wheel, unless you want to of course.. Than I'd suggest reading up on DB architecture, which is a little more complex than storing and retrieving files :)