I've seen the same questions posted over and over so figured I would start one thread so there aren't a ton of them.
If you have an iPad and a wifi printer use the following steps to get your iPad printing wirelessly. This is for if you DON'T have one of the HP printers that works with AirPrint. Been Googling around and this is the easiest instructions I've found so far:
Enable Airprint in Windows and use any printer