Wireless computer speakers typically come in a 5.1 configuration. This means that there are five speakers in total as well as a standard subwoofer. In these configurations typically only the rear speakers are wireless, as the front speakers are designed to be placed close to your computer. Hooking your PC up to wireless speakers involves hooking up the wireless transmitter that came with your speakers.
Unpack all of the equipment for your computer's wireless speakers. You will have a wireless receiver that plugs into your computer, a wireless transmitter that plugs into your speakers and at least two wireless speakers.
Connect your wireless speakers to your wireless transmitter. The speakers themselves will have wires coming off of them that plug directly into the speaker inputs on the transmitter. Plug your wireless transmitter's power cable into a wall outlet.
Connect your wireless receiver to your computer. Find your available sound card inputs (which will be color coded) on the back of your computer and plug the transmitter's cable into the necessary inputs. Some wireless receivers will plug into only one sound card input, while some may use all three standard sound card inputs. It depends heavily on the model and brand of wireless speakers that you've purchased.
Plug your wireless receiver's power cable into a wall outlet. With both the receiver and the transmitter on, your computer will automatically begin sending audio information to the wireless speakers, which you will hear immediately.