It is at the State Fire Academy, 8895 East Main Street, Reynoldsburg, OH 43068-3340. You can't miss it. Pull onto the academy grounds, park where the nice people tell you to and follow the crowds to the fire trucks and vendors. Oh yeah, buy something off of the youngstownfire.com people too.
You can check out http://www.coafaa.org/ for more information including a flyer for the event and see pics of previous years musters.