It's a lottery these days, and you have until the 22nd to enter. Here is the registration.
It's a fun race, but not the most serious. A lot of walkers. If you have a qualifying time in a 5k, 10k, or half marathon put it down. People with no times start at the back, and you don't want to be at the back.
Just to overclarify, there are basically two elements to it - the lottery for limited number of spaces in the race (though the odds are quite high of getting in, as I understand it), and a qualifying time for corral placement. The qualifying race simply needs to be USATF certified.
To follow on the above post, the flyer will advertise that it is a certified course and usually mention that it is a peachtree qualifier. Word to the wise, the race wont be chip started and if it is only the recorder gun time will count towards your time. If you are fast enough to qualify make sure you are in the front of you qualifying race.