I should have thought it was the responsibility of the dealer, who sold you the car to have it coded for you. Where you made aware on purchasing your car that the spare key card was uncoded?
I found this on the web, so not sure if it works but its worth a try:
"take out the batteries in the key fob. put new batteries in the fob. put the key fob, with key into the ignition socket and keep the "lock door" button depressed for about a minute. withdraw the fob and put it back into ignition as normal."