Dell isn't on the list of supported printers, but don't dispair there are several work-arounds.
------------------------------------------------------
List of supported AirPrinters.
http://support.apple.com/kb/HT4356
----------------------------------------------------
printing to a non-airprinter from an iPad
To print from the iPad your going to have to install some more software:
-- many printer makers have iPad applications for their printers. Look in the app store
-- generic software like Printopia
iPad Print Applications -- usually free:
Samsung
http://itunes.apple.com/us/app/samsung-mobile-print/id429611283?mt=8
HP App, ePrint Home & Biz
http://itunes.apple.com/us/app/hp-eprint-home-biz/id299531647?mt=8
http://h10025.www1.hp.com/ewfrf/wc/searchResults?tmp_product=HP+Photosmart+5515+ e-All-in-One+Printer+-+B111a&product=5063608&tmp_qt=eprint&cc=us&dlc=en&lc=en&su bmit
-- At one time Dell printer were rebranded LexMark printers so try this lexmark app.
http://itunes.apple.com/us/app/lexmark-mobile-printing/id469415392?mt=8
Generic Software:
You can connect the printer to a computer and install software on your iPad/computer to print from your ipad to the comptuer then to the printer.
example:
http://www.ecamm.com/mac/printopia/
Should you have some office printer that are connected to a computer there are print enablling applicaionts you can run on the iPad to print to such printers.
For Windows, try: PrintBreau, or PrintCentral.
printcentral Pro
http://itunes.apple.com/us/app/printcentral-pro/id426362921?mt=8
Source: https://discussions.apple.com/thread/2729284?start=0&tstart=0
this google query will give you more options
ipad airprint via mac