Can you confirm that your iPad is connected to the same wi-fi network as your printer? If yes, then when you select the option to print a dialog box should appear asking you to select printer, click that and it will search for your printer, once found click it and your document will print.
I hope this has been of some assistance
It has nothing to do with iOS 6.
Is the printer on the 'airprint enabled' list of printers? Whats the printer model number?
Print from iOS device to virtually any printer