But yours may be different - read the Owners Manual.
When driving you should be able to tell by the feel, sound and rpm's whether you are in overdrive or not. If not put it in Drive and as you are driving shift the shifter in to overdrive. Unless you are driving very slow you should be able to tell if it went into gear or not.
"Overdrive" is simply the top gear in your transmission. It's the 5th 'speed' in a 5-speed trans, or the 6th 'speed' in a 6-speed trans. If you use the gear selector properly in a car with an automatic transmission, then it's on all the time.
If your gear selector has both a "D" and an "OD" position, just put the selector in OD and leave it there. The transmission will select the proper gear for your speed and driving conditions all by itself.
Should be a "Activated" light somewhere, end of gearshift lever?
Do you have a tach? RPMs will drop about 600. No tach? Just listen, you will hear it kick in.
Most often there is an "O/D Off" light on the dash.
