Read your motherboard manual.
It will have a diagram of the pins.
If you don't have a manual, you can download it here: http://www.asus.com/Motherboards/Intel_Socket_775/P5GZMX/#download
The reset switch is not polarity sensitive. connect it to the two RST pins.
The led lead IS +/- sensitive. If you get it backwards, the led will not work, and you can just reverse them. No harm will come.