When you are staying at a Disney Resort, about 30/35 days prior to your trip you receive mail from Magical Express (if you are using it) with tags to affix to your luggage so they know to grab them and take them to Disney. Be sure they have the correct name and resort on them.

You'll get ME vouchers and directions how to get there from anywhere in the airport. Also, from Disney Travel you receive decorative, fun luggage tags, vouchers and other paperwork. The envelopes usually have Mickey and pals and the monorail.