Hi amcmillon, welcome to the DIS!!
You only need your resort confirmation number if you are trying to book dining reservations within that 180+10 day booking window kathie859 mentioned. Everyone can make advanced dining reservations (ADR's) 180 days in advance, but if you are staying on property, you can book ADR's an additional 10 days past that.
For example, anyone can make ADR's today for January 10, 2009. If you are staying on Disney property, you can make ADR's for ten days past that date (January 20, 2009). You only need your resort confirmation number in this situation.
Enjoy your trip!