Basically a wireless printer broadcasts messages on your network, that your PC sees and responds by listing that printer - it sounds like you're already setup to do this.
So to print on your iPad, your wireless printer has to broadcast using a protocol that it can understand, and that's an Apple specification called AirPrint.
Once you have an AirPrint compatible printer up and running on your network, it's as simple as choosing the print option on your iOS device and you'll see it by name ... select, copies, etc., print. Done.
Some printers broadcast that AirPrint protocol right out of the box, if they're not compatible, you have to connect something to the printer that can broadcast for it. That comes in two flavors: a standalone print sharing box or a computer, connected to the printer, then sharing it out using AirPrint.
The latter means that computer has to be up and running to use the attached printer, the box is a little device that wedges in between the printer and network and provides the broadcast.
Here's an example of all three options:
AirPrint out of the box printers (from Brother):
http://www.brother-usa.com/printer/cloud/airprint-app.aspx#.UOxhWqViiRY
AirPrint server device:
http://www.lantronix.com/it-management/xprintserver/xprintserver.html
AirPrint computer "server" app:
http://www.ecamm.com/mac/printopia/