How can you find information about a 5 cent Internal Revenue Certificate Stamp dated 1866?

Revenue stamps are part of a group called "Back of the Book" stamps. They will be found in the 'back of the book' or the back of the catalog for US stamps. The US Specialized catalog will list it, as will most of the other US catalogs. You can usually find a copy at your local library. It will also tell you when it was used and how it was printed among other information.