Audio Jack Problem

I have a Negative & Positive of a Audio Jack for computers from which i need to make a extension cable for it, the jack is similiar to the below one>
**broken link removed**

I want to know what is the Significance of Jack-Pins in making the speaker work in DIFFERENT MODES LIKE "Stereo / Mono" / "Right / Left"...
Also what are the connections i require to make FOR EXTENSION CABLE?

Another Doubt is " As soon as i Plug my head phones to a negative jack provided in woofer, the speaker automatically turns off, making the sound audible in head phones"

The plug you show is used for transmit and receive or for left and right stereo signals. Its cable is usually shielded audio cable but hedphones extension cables are made without the shield then a tx/rx or stereo signal will probably pickup mains hum.
For an extension cable then simply repeat on the jack which wire connects to which pin on the plug. Use an ohm-meter to see which pin is which..

Jacks are made that switch off speakers when something is plugged into them.