Re-program Garage Door Opener

I purchased a 98 DeVille that has a garage door opener in the headliner between the two cabin lights.  The opener still works for the previous owner's garage door, but I would like for it to work on my own garage door.  I have no instructions for programming this remote.  Can you help me?  Am I going to have to go to a garage to get this thing programmed?

Pretty sure it's in the owner's manual. If you don't have one I look and post details tomorrow. Its -25 and I'm not up to going out side again tonight.

Engine is off during this process:
 
1. Hold down outside two buttons until red light flashes rapidly, approx. 20 seconds. release buttons. This establishes mode for re-programming..
 
2. Choose a channel to program.
 
3.Hold end of handheld unit against front surface of universal transmitter of car. Make sure you can see the amber light.
 
4. Press handheld button and one of the universal buttons.
 
5. Hold both buttons until the amber light on the universal flashes slowly then rapidly. The rapid flashing could take up to 90 seconds, but it indicates the programming has been successful. Release both buttons once the amber light flashes rapidly.
 

Thanks!  This WORKED!  I am amazed that it was that easy.  You just have to know the right buttons to push.

Glad to be of help.  It is in the owner's manual. If you don't have one I suggest obtaining one. They come up on e-bay form time to time.

My 99 Deville has a garage door opener with a single amber indicator light.  My garage door opener is a Genie with rolling codes.  I just tried the programming method above without success. I've also tried the car's owner's manual method and the Genie manual's method...all no go.  The door opener operates perfectly with the Genie handheld transmitter of course.
 
I read that some Caddy openers have a green light either instead of the amber light or in addition to it.  Do I need a green light opener for my Caddy for it to open the garage door because it has rolling codes ?