CD key help

I recently bought the Supreme commander Gold edition from amazon. I have The instruction manual for supreme commander and the CD key. So I can play that fine, But I also have a tech tree thing with Forged alliance printed on the front. I was searching for the CD key for FA, But I was unable to find it anywhere. Is there something I am missing here? what can I do about this Please Help me.|||thers no need to post this in 3 differmet places