How do I program key Mercury Sable?

I lost one of my keys for my 2003 Mercury Sable. I read that the dealer charges over $100 for this. I think I found the blank on google. How do I program the key. I did a search in this forum and must not have put the words in right.
Or can this even be done? I also only have one remote (not sure what you call it) thing with the buttons that unlock door trunk, etc.
Thanks

Programming a Ford PATS Key - http://www.fordf150.net/howto/patskey.php

Programming a Remote - http://www.fordf150.net/howto/reprogramremotes.php

I lost one of my keys for my 2003 Mercury Sable. I read that the dealer charges over $100 for this. I think I found the blank on google. How do I program the key. I did a search in this forum and must not have put the words in right.
Or can this even be done? I also only have one remote (not sure what you call it) thing with the buttons that unlock door trunk, etc.
Thanks
If you have only 1 key, you need to see the dealer.
If you have 2, there is a programming procedure.
I bought my keys on ebay for about $20 each and had them cut locally.
My local key shop sells them cut for around $25, which I would recommend.
Remotes can be bought on ebay...

what about programming the keypad on the driver side door?

programming ford keypad - http://www.fordf150.net/howto/keypad1.php

Can I insert the same key 2 times and then the new key to program it???