i sell these at work, you get a disc with it, the disc loads the software onto your laptop or computer, it connects that way, you can also use a usb lead though, (not supplied)
We have a wifi printer but my husband can't get his computer to print to it so he has to email it to my son and then print it (wirelessly) from his Mac.
Assuming you have a wireless router you can buy a wifi card very cheaply for your desktop (less than a tenner), open the case and pop it in. Very easy to do.
If you don't want to open your case you can buy a wifi dongle that uses a USB port, probably around the £10 - £15 mark.
Both these solutions turn your pc in to wifi enabled so you can connect to the router and the printer.
I repeat what I said... post this sort of question then the correct section, then you will get proper answers, not the "I think" or the "I've heard" answers!!!!
most of the replies to this so far are a load of rubbish!
I bought a little aerial type wotsit that fitted into the USB of my old desk top to be able to run it wirelessly when I moved it into another room, cost about £10 from Scan. SHould then pick up a wireless printer too.