I'm looking for a free AirPrint software download for my iPad

Airprint is included in iOS you do not need to download anything.

See this article for details:

http://support.apple.com/kb/HT4356

There is no AirPrint software to download. It is part of your iOS system software. The printer you use must support AirPrint. If it does your iOS device will find the printer and print to it.