You should have gotten 3.5mm to dual RCA male connectors. The male RCA's will go into the speaker's amplifier with their color coded other end(male 3.5mm jack goes into the ports on the back of your motherboard.
F = Front
SW = Subwoofer
Cen = Center
SR/SL = Rear right/left satellites
Yes i have 3.5mm to dual RCA male connectors. There are only three cable end for the motherboard port i.e FR-FL , SR-SL , SW-CEN. For these three which one should i connect to motherboard ports out of six ports ?