Dear Kayla:
You should first fiind a unit that includes members who do civilian impressions. Because of your age, you would have to be "traveling with your family". You could be a young woman from a large city, small town, or farm. It's best to develop a persona that you might have some familiarity with. I.E., if you grew up in St. Louis, in a large Irish Catholic family (I mean in the 21st century), you would not be very familiar with life on a farm in either century. Attend an event and talk to other young women who are reenactors, to give you some pointers. Do some background reading on women's roles in the 19th century, and how to "fill in" your background. In this hobby you never stop learning.
Good luck! Reenacting is a great hobby and I have been doing it for 15 years - with a hiatus of about 18 months due to loosing everything in Hurricane Katrina. Due to the kindness of a friend, I was able to participate in the Battle of New Orleans event (War of 1812).
P.S. DO NOT USE GONE WITH THE WIND - this book has NOTHING to do with what life was like in the Deep South, or in the way young women behaved in the 19th century. There are many excellent resources out there.
Faye Dufour