My book is already in the iBookstore. It is called 'There Is Something about Gina - Flourishing with Diabetes and Celiac Disease.' I just need to update it and I was told to use iAuthor hence the extension issue. I
originally published it via iProducer.
Thanks for any assistance you can offer.
I originally published it via iProducer.
I don't know why someone would tell you to use iBooks Author. It cannot read or produce epub and it can only update books which have been made with it, and for which you already have the .iba file. Perhaps they were thinking you would want to transfer your content to iBooks Author, which means essentially redoing the book via copy/paste, etc. But the resulting .ibooks format can only be read on an iPad and not any other device.
To update an existing epub book, you should normally use the same app you produced it with. For example, Apple's app for epub is Pages. You would have composed in that and then exported to .epub format, but kept a copy in .pages format for future changes. Many people use InDesign and they would keep the original file for future changes and reexport to epub.