Hi how can i set up altec lansing vs2121 computer speaker to my desk top ?

Looking at the manual http://www.alteclansing.com/downloads/EUR/VS2121%20manual.pdf page 3 of the pdf says Connect the lime green 3.5mm stereo cable (hardwired into the right satellite) to the lime green input labeled ?FRONT? on your sound card. So your right speaker should have a cable with a green end that plugs into your standard audio out jack If you have multiple outputs and don't know which you are set up for, then turn the speakers on and up, put a long song on, and plug that green wire into every jack on the PC! If you've got no other issues you'll hear something! Good Luck