The HP 6500 is wirelessly connected to your network?
It is on the list for AirPrint supported printers, so it should work without any setup, as long as the printer and iPad are on the same wireless network. Your iPad needs one of the newer firmware updates though, I think 4.3 is the minimum.
If that still doesn't work, you could use a third-party app, such as print'n'share to print to network most printers. The only requirement here is, that print'n'share needs to run in the background, so it has to be started at least once after every reboot.