Pretty tough to get a new forum going. I've seen a lot start up and fail within a couple months. Contests work, but once those stop, the people stop coming. If you offer good content and get people to interact it will slowly build.
Sorry I forgot to mention. One of the sub-forums you could have that may peek and keep some interest is a 'buy sell trade' thread! People want to get rid of stuff all the time and many throw it out because they don't want to do all the work of getting a yardsale ready!
Use social media platforms that allow for local targeting and then go for targeted visitors in and around Alabama.
Word of mouth is probably going to be your best bet to get started. Keep relevant, interesting content going. Don't lose hope or focus though, a forum takes a good deal of time to build. It will happen eventually if you stick with it. Give people a place to talk, and they will come to talk.
Only basic promotion and some give big contest to someone who are the best posting in the forum with useful post. Then you will get lots of members in your forums. (((((Just Give Them Award))))