The dining plan is actually pretty simple. You pay a set amount in advance, based on the number of nights you are staying. For that money, you get a set number of dining 'credits' to be used whenever you want during your stay.
With the standard plan, for example, if you were staying for 3 nights, you would get 3 table service meal credits, 3 quick service meal credits, and 3 snack credits. When at a restaurant or snack stand, simply give them your hotel key/park ticket. It keeps track of your credits. They will redeem one of your credits for that kind of meal or snack, and even give you a receipt showing what credits you have left.
There are limits to what you get with each credit. A meal credit typically gets you an entree, a dessert, and a non-alcoholic beverage. If you want to get something on top of that, you just pay for it as you normally would.
For more information either send me a follow-up question from my bio page, or view the PDF brochures for the
different dining plans on the website.
Have a magical (and delicious) vacation!