I would love to help you because I live in the south (Mississippi). It's hard to help right now because your question is so vague, but if you get more specific, I would love to help you any way I can!
Like Flying Geese, I'm not sure exactly what you're asking. The same way you'd write about any other setting -- describing the locale, the weather, the topography, the types of businesses, the attitudes of people. A lot will come across through your characters, and a lot will come across through where the action is occurring.
'the south' covers a variety of very different locales and locals, as well as speech patterns... so be sure you are researching the exact area where your story takes place and where each of your characters hails from...
