If you have bought or built a homemade trailer, the process of registering it for road use in your state is slightly more involved then what it takes to register a commercially built trailer. There are slight variations on the procedure from state to state, but the general requirements are the same.
Gather all your receipts for any material used in building your homemade trailer. If you used or modified a commercially made chassis, make sure you have all the receipts associated with that work.
Take the trailer to your nearest VIN inspection station. You can tow the trailer to the inspection station as long as the vehicle towing it is registered. If you have a commercially built chassis with a VIN number, the officer at the station will conduct a NCIC check that will verify the number was not reported stolen. If your chassis does not have a VIN number, the officer will assign one and affix the VIN plate to the frame and give you the necessary paperwork.