Q: How can I connect my iPad to my wireless Hp  Officejet Pro 8500 A909g ?

Are you trying to connect the iPad directly to the HP or using your wifi network?

HP published this page that may help:

http://www8.hp.com/us/en/ads/mobility/overview.html?jumpid=va_r11400_eprint

A909 does not show as an AirPrint capable printer:

http://support.hp.com/us-en/document/c02623193

About AirPrint - Apple Support

You may wish to search the AppStore for an app that could help you.

Using AirPrint, just connect your wireless printer to the same Wi-Fi network as your iPad. Not all printers work, Apple has a list of them here: http://support.apple.com/en-ca/HT201311