If it has not got a wireless card on it you can pick up a wireless dongle which plugs into your Usb slot.They are not very expensive.£10-£20 should do it.
When you connect it Microsoft should download the driver for it.Whether you have to reboot for it to take affect i cannot remember.
I did it on my 6 year old computer with no problems.
Maybe wait and see if anyone can come up with a better solution.
If it is a laptop you are on about it may already have a wireless connection and it would just be a matter of switching it on.