The AIR SDK can be downloaded at: http://www.adobe.com/devnet/air/air-sdk-download.html
The Flash Player can be downloaded at: http://www.adobe.com/support/flashplayer/downloads.html#fp11
For more information on the release, you can read the tech note: http://helpx.adobe.com/flash-player/release-note/fp_115_air_35_release_notes.html
If you forgot how to manually update Flash Professional to target a new version of the Flash Player, you can read this blog post. Flash Professional CS6 has AIR SDK management available under the Help menu.