First of all, your PC should be compatible with the 5.1 sound system. Your PC should support an audio system with 6 channels. Check on the backside of your computer whether there are extra connectors to connect the speaker wire of the rear out and subwoofer.
These connectors are coloured, and the wire that you need to plug in also has the same colour. So, there is no confusion. For better audio quality and sound output, you can download Boom 3D on your pc. Moreover, if you use Mac, Boom 3D has 5.1 multichannel audio support. There is no requirement for different connection wires and setups. Just download and enjoy the different features of Boom 3D. Try the 30-day free trial before deciding to buy.