You should be confused because the woofer isn't labeled or color coded clearly.
The back of the woofer has 4 inputs labels A (light blue), B (green), C (orange), and D (black).
Normal PC audio outputs are lime green for L-R front, orange for center-sub, and black for L-R surrounds.
The only way to find out how to connect it is trial and error.
Use the lime green 2 channel front output of the PC and connect it to each input. All the satellites have to be connected.
Turn off the sub when you make a connection and start with the volume turned down so you don't damage anything.