How to optimize an overdrive button?

[badaveil]

I have been driving a manual gear car most of my life so when I got my first auto gear car, this thing called an overdrive button in the gear shaft came into my life. I am not sure if I am using it correctly as there is not much info on that and many people I ask NEVER even use it at all. But it's it's there and the manufacturer took pain to assemble it into the car how does one exploit and optimize it while driving?

 

[HugoBoss]

Maybe this will help...http://voices.yahoo.com/what-overdrive-button-automatic-transmission-1761389.html

 

[HDi fun]

My Primera had one of these. All it does is lock-out (ie. make unavailable) the top gear of the transmission and the torque converter lockup. In this mode there will usually be an indicator light on the instrument panel. Mine was orange and labelled O/D OFF

Normal mode is light off and all gears available.