Looks like you listed how the sound card is described in the control panel. Do you know the name of the sound card hardware?
The reason that I ask is because I want to help you with understanding your connections. If you had three 3.5mm output jacks on a 5.1 sound card, then connecting that sub would be relatively easy. If you only have a single 3.5mm stereo output, it might be difficult...but I might be forgetting a simple solution.