Hi April!
You said you purchased the Fantasmic! Dinner Package, but perhaps you are referring to Disney's Dining Plan?
The Fantasmic! Dinner Package is something that you reserve (but do not pay for in advance). With this dinner (or lunch) package, you get to choose among three restaurants at Hollywood Studios. They are The Hollywood Brown Derby, Mama Melrose's Ristorante Italiano, and Hollywood & Vine (dinner only). You will receive a voucher during your meal that entitles you to preferred seating at Fantasmic! that evening. Here is
more information on this program.
If you do not have the Disney Dining Plan you order whatever you want and pay for it accordingly. If you do have the Disney Dining Plan (which I believe is what you're referring to), you will "pay" for your meal by using your pre-paid dining credits. There are different Dining Plans offered so I can't really go into more detail without knowing which one you've purchased. I don't want to give you any misinformation. Here is a
link listing all of Disney's Dining Plans.
I hope I've cleared this up for you a bit. If you have any other questions please come back and ask us. We love to help! Have a wonderful trip!