Epson Stylus SX235W: How to Set Up Wi-Fi?

Hello,

I got a printer, the Epson Stylus SX235W, a year ago. This printer is supposed to connect via Wi-Fi to the computer so that I can print without plugging a cable into my computer.
When I set it up on my Acer laptop with Windows 7 Home Premium, I couldn't connect the printer via Wi-Fi, so I connected it using a cable.
I got another laptop at the beginning of the school year (provided by the school), a Dell model, the Vostro 3360, with Windows 7 Professional.
I would like to connect the printer via Wi-Fi this time on this computer. However, I have already tried to find information online, apparently, I absolutely need the CD, but unfortunately, I can't find that CD...
I would like to know how to connect my printer via Wi-Fi (without a cable) to my Dell computer, and without a CD....

And if possible, also how to enable Wi-Fi between my Acer PC and the printer (since the connection is only through a cable for now) without a CD as well!

Thank you in advance :)