Hi Denise,
It is recommended that you book dining reservations at WDW early, but as long as you're willing to be flexible in both where and when you eat you should be able to find some dining reservations for your stay.
There are 2 ways you can pre-book, either online via the dining pages of
www.disneyworld.com or by calling 407-939-3463. Personally I like the online system as if the restaurant you require is unavailable it often gives you alternatives. You can also try and book once you're in WDW, as you enter a park just go to any guest services where they'll be able to check availability for you!
I've just had a look online for you, I assumed you were a party of 4, and there are several openings at lunch time at the Rose & Crown, Biergarten, Nine Dragons and many others in Epcot for 4 people on the 23rd September.
Good luck and have a fantastic trip,
Jo