I am trying to print from an iPad 3 app. It says "No AirPrint Detected"
Air Print is a term referring to printers made specially with iDevices in mind. Those printers have drivers in them to see iPads and the iPad comes with drivers installed to seamlessly print to those printers. (same basic premise as the difference between color and black and white printers)
If it says no air print detected, then chances are you dont' have a wireless printer that's also air print enabled.
has more info.
If you need/want to print there are other options beyond air print printers. Many printer manufacturers have apps or ways to allow you to print from devices. And there are plenty of third party apps that will also enable printing. I use Print n Share with my non-air print Kodak printer