Christopher L Middleman wrote:

If I have a book scanned into koha and I want to use a barcode already on the book where do I find the page in koha to input the barcode? In other words where is the input section for that barcode?

In the 'Items' section for each title (Koha calls them 'biblio') you have entered in your database. Each item can have its own barcode, and it should be automatically assigned by Koha when you enter the first item. You can modify the barcode there and then use it in, for example, the 'Circulation' module which is an easy interface for people delivering books to users. HTH, Jose