If you get out of Atlanta before 9am 85N to 316 is the route to go. If it is much later than that, 316 becomes a parking lot (literally will be moving 10 miles/hour) so you will want to continue on 85N until you get to 129 (exit 137). That 129 will eventually turn into Prince street which goes straight into Athens.
Parking is a nightmare and they love to tow. I would just google the stadium and look for the closest/cheapest lot possible.
If you want to save a headache, wake up and leave at 7am, beat traffic, and find a good pay lot.