The Adobe Developer Connection has links to lots of reference and learning material:http://www.adobe.com/devnet/air.html
Before installing an AIR file, a desktop user will have to install the AIR runtime. You can install from a "badge" (a small Flash program) on a web page which can detect whether the runtime is installed and prompt the user to install it if necessary.
For a native executable, the install process will prompt the user to install AIR if needed.
Sorry to barge in. Could you please tell me what a web designer can do with Air? Does it require programming knowledge to use it? Sasi
In a nutshell, AIR lets you take a SWF file or HTML pages -- something you've created in Flash -- and make it into an installable application that will run on a desktop computer, mobile devices (iPhone, Android and the upcoming Blackberry playbook tablet), and some newer TVs, DVD players, etc. (HTML-based apps are only supported on desktop computers at this time.)
If you can create something in Flash that would be useful in these environments without programming, then I guess you could get by without programming knowledge. But typically at least a small amount of programming would be needed.