The Gobble Jog starts and finishes on the Marietta Square. If you want to map it, enter "Glover Park, Marietta, GA" as the destination address. The Google Map link is here.
Here is a map of parking on the square. You will be able to park for free at any of the city parking garages or parking lots near the Marietta Square, but you should be aware of road closures. The roads that go around the square (North Park, West Park, South Park and East Park) will be closed all morning. The blocks of Power Springs Street and Whitlock Avenue closest to the square will also be closed. The roads on the race route will close at 7:30 a.m (the route is below). You'll see that the route crosses North Marietta Parkway (120 Loop) in two places, so you won't be able to cross there when runners are on the route.
The map of the route is here.