As already stated, one way to print from the iPad is by using Apple's wireless technology called AirPrint - check out this Apple support article HERE for a list of printers that are supported.
Now there are plenty of non-AirPrint options for other printers - this is an oft discussed subject, so a little searching will likely bring forth posts/threads to help.
For myself, I am using a program called FingerPrint (information HERE) to print to my Canon printer; a small program needs to be installed on your computer attached to the printer and both the computer & iPad need to be on the same Wi-Fi network - just $10 - good luck!