nope. your car automatically shifts into overdrive when needed. it really isn't something that you will feel or see or will win you a million dollars. it simply is another gear in the transmission.
The term "overdrive" comes from a little while back, when it was un-common for a the transmission output speed to be faster than the input speed. in transmissions that had gears for this (often, the engine spins 2 times for every 3 or so times the drive-shaft spins)... those transmissions were reported as "overdrive" transmissions, because direct drive is a 1:1 ratio.
Now that it is relatively "easy" for transmissions and engines to use overdrive... the term is slowly fading away.. as it is just something that is expected of cars.
2006 - Charger - Black - 392 HEMI
1999 - Jeep - Cherokee Sport - 144K miles - STOCK
1966 - Charger - Primer Red - heh... engine on the floor next to it.....