The University of North Georgia has a WW Club that seems pretty active. They're on FB (North Georgia College Whitewater Club). You could also try the FB page 'The Whitewater Kayakers Network' - lots of GA people there. Maybe Georgia Canoe Association and Atlanta Whitewater Club too.
You said that you're new to WW but are interested in paddling class II, III and IV. What rivers have you paddled?