Call the columbus office ask them who is doing the exams now, Then contact that party to see about getting a list of the books needed.
They should provide you with a list of books that are allowed in the room for the test.
Buy those books and read through them. Learn where things are in those books.
And make an apointment for the test.
Some towns and counties still don't require that you be registerd with them. Most Do.
Heres the address and phone number to columbus
Division of Industrial Compliance
Ohio Construction Industry Licensing Board
6606 Tussing Rd - P.O. Box 4009
Reynoldsburgh, Oh 43068 - 9009
If you try to fail, and succeed.
Which have you done ?