need insight on how to wire up aux plug

Ok heres the deal,

I bought a panel mount aux input to plug it my avic d2. Im trying to find how to plug it to my 2 rca jacks.  There is 2 wires for each rca wire so I have a total of 4 wires. I figures if i use the outer wire on each and put it on the middle hump of the 1/8 audio jack I get the sound but it not loud, I really have to raise the volume. Im not sure if I need to use the other wires or where to put them... I also ge a buzz sound trough the music... If anyone can help me that would be much apreciated.. thanks

The following info pertains to the male plug that plugs into your jack.

The tip of your cable is the left signal wire.  The middle ring is the right signal wire.  The ring closest to the cable is the ground. this is where you should connect the 2 outer conductors of your cable