To be able to use the printer in the manner you are trying.. You first have to add y our officejet 6600 to the google cloud print service. To do that, you need a Chromebook, a PC, or a Mac.. ( once its registered you no longer need the computer)
This page shows you how to register the printer with google cloud print.. So that the ipad using the same google / gmail address can then print to that printer from anywhere.. meaning if you are at the store you could cue up a print command and it would send it to your printer at home.. So you need to set up cloud printing first, heres how
Once that is setup you would t hen see your printer as an option in google cloud print..
Otherwise, you need to use an alternate printing app.. What app are you currently using? Airprint? Or are you using the HP mobile printing app? If you arent using the free Hp mobile printing app, you can get it here.
As you see, it has an email printing feature.. So this would be a workaround to using the Google cloud print.
But you will have to have one of these two apps and the print needs to be setup with each, or either.
If you get stuck or have further questions, you are welcome to respond.
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