I have a wireless Epson printer at home, so let me generally cover the steps:
1) on one of your PCs, start installing the software provided on the disc. At some point, you will be asked to plug the printer into the computer via USB. I cannot recall if at the latter part of the set-up it asks about setting up the wifi connection, but I believe it does.
2) I recall having to enter the SSID and password of the wifi network directly into the printer itself.
3) if, as stated above, the model is not AirPrint compatible, make sure you download the app Epson iPrint - it helps to connect to most Epson wireless printers that are not AirPrint compatible. It also gives your iPad scanning capability