If you're talking about getting the free dining plan, this is what you get.
1 Table Service (places where you sit down and they serve you your food.)
1 Counter Service (Like McDonalds but much much much better.)
1 Snack (Anything under 4 dollars that is 1 portion. I personally love getting chocolate crossiants with my snack credits. As well as cheese fries.

)
All that for one day. For the table services you need to call and make reservations.
To work all this...when you check in they'll give you your Keys to the World card (it get's you into the your hotel room, into the park etc). When you want to pay for your food, just tell them to swipe your card. Also, at check in you can give them your deibt/credit card number and you can use your KTTW card to buy anything.
*phew* For more information, read the Theme Parks and Strategies Board, or the Restaurant and Resorts board.
Free Dining plan is usually offered during late August to Late September. You can get it when it comes out around April, the exact dates will be out then as well.
Oh...
Table Service - Entree and Dessert and Non-Alcoholic Drink. You'll have to pay for your own tip and appetizer if you want it.
Counter Service - Entree, Side, Dessert and Non-Alcoholic drink.