new and nieve to a 99 cougar 24valve v6 auto

Hi Norm and welcome to the forum - I've got a manual so I wouldn't have a clue but I'm sure that someone with an auto will be along before too long with an answer to your question.
 
it turns the overdrive off, the box is three speed and overdrive, so if you are in slow moving traffic switch off overdrive and the box doesn`t change as often thus doing less work.
 
Welcome to the club Norm. I am sure you will have many happy hours of motoring in your new cat!

Whereabouts are you in UK? It is useful to know where members are - you never know when you might need to contact one about a problem!! Members are happy to help each other out when we can. :):):)
 
Welcome to the club Norm. Hope you get to grips with the button settings on your auto. I drive a manual, so I have no idea about little green buttons or any other coloured buttons...smarties perhaps??? lol!!!!!
 
Well as i've got the manual in front of me I thought I might help you out a bit more.

There are two buttons on the selector lever, the one on the side is for selecting R or 2 (but not moving between position 1 and 2) it also is used to move out of P (while depressing the brake pedal too) and the one under the grip is to select or de-select overdrive (an indication will show in the trip meter section on dash) (if the gear-box is changing up and down from 4th and 3rd a lot then de-select overdrive)
[max revs in N and P is 4100]
ECONOMY MODE {E}
In this mode, the transmission changes to a high gear earlier and to low gear later. Use for normal driving.
SPORT MODE {S}
High gear selection is delayed so that the engines power is fully used. Downshifting takes place at higher engine speeds, e.g. In a quick overtaking manoeuvre. The control light illuminates in the trip meter window when sport mode is selected.

If {!} shows in the trip meter display then the auto-gear box has a fault.

The green button Phil refered to is situated under the passenger side of the center console (if memory serves me correctly) and is used in emergency occasions to de-select P mechanicaly (in the event of power failure)