Your best bet is to "Google" it. Then you will get a good starting point on your requirements for your certificate and dealers in your area.
Or ask in the "local region" (I'm sure it's called something like that) here on Lawnsite. That way you might find a few people who had to go through what you're wanting to do. And if they know you're not in their city, they might help you.
2013 Ford F450 Super Duty Truck
2010 Exmark Lazer Z 60" deck
2012 ExMark 30" Riding Aerator
2011 John Deere Pro Gator 2020a
2011 Lawn Solution Dual Hyrdo Aerator 24"
2011 Echo Handheld (trimmers to power pruners)
2007 Big Tex 4ft metal high side 7' x 12' Trailer
2012 PJ 7' x 16' Dump Trailer
2014 Vintage 8.5' x 24' Enclosed Trailer
2012 Ecolawn Applicator model 200 Compost Spreader