Yes, it's an output jack, not an input. The pickups generate voltage which is sent out to the amp (which then amplifies the signal). But it's just a 1/4" phone jack, not specifically an input or an output jack -- its usage determines whether it's an input or an output.
Anyway, the jack needs to have two connections -- hot and ground. That's two wires -- hot from the center terminal of the volume pot to the tip connector of the jack, ground from the back of the pot to the ring/sleeve of the jack.
If your jack has three terminals, it's a stereo jack or a switching jack. You can still use it, but you'll only use two of the terminals. If you study the jack for a bit you can figure out which terminal connects to which contact. You want the tip (the long leaf spring thing with the bend at its tip that fits into the tip of the cord's plug) and the sleeve (the tube, the outer part of the jack where you insert the plug).
Here's a fairly common Strat wiring diagram. http://support.fender.com/service_diagr ... A_SISD.pdf
There are diagrams for other Strat models here on Fender's site linked at the top of this page: Support > Service Diagrams