Hi Maureen!
The Epcot International Food and Wine Festival is a highlight for anybody visiting in September or October when the festival is running. Basically, it is included in your admission to Epcot in the sense that you can visit the festival booths, welcome center, enjoy the concert on select nights, etc. However, food and beverages cost extra and there are some special events tied to the festival that costs extra as well, sometimes substantially. You can get more information online
here. On that page, you can click for more information, such as clicking on the link for "Special Festival Experiences".
The main part of the festival, in my opinion, is the food and beverage booths that are installed around World Showcase Lagoon in Epcot. More than 25 international marketplace kiosks offer tapas-size portions of regional specialties for about $5 per serving (on average). Countries in the past have included Australia, Brazil, France, Ireland, Poland, and Greece. As you wander World Showcase Lagoon, you can stop by the various booths and pick up a snack. In fact, "eating around the world" takes on a special meaning during the festival! It's a lot of fun!
If you can, plan on going to Epcot on Monday - Thursday. Friday, Saturday, and Sunday are typically more crowded due to locals coming into the park to enjoy the festival.
Enjoy planning and write back if you have any more questions!