This a world-famous series. I think I don't need to give you more info, but if you want to read more, check this out:
http://en.wikipedia.org/wiki/Avatar:_The_Last_Airbender
This is a TORRENT download (actually a magnet link), so you'll need a P2P client as uTorrent and Vuze. The pack includes the three books in DVD5 full iso with extras, languages included: US English, Latin American Spanish, some discs include French and some others Portuguese. These are discs for regions 1 and 4.
PLEASE NOTICE: I do not own or upload these files, I just found the pack on a web search.
The password for the files:
www.intercambiosvirtuales.org (Type it, don't copy and paste)
The link: Download with magnet link
Official website
If you like it, please buy the series.