If you used iBooks Author and have created the correct size screen shots, book cover and a preview sample of upto 15 pages.... click PUBLISH in iBooks Author and follow the flow when iTunes Producer opens.
If you have an iTunes Connect account - and you need one..open it and sign in, and find:-
Prepare your content for delivery to iTunes. click the link and find on the right of page:-
That may help help you.
I am also having serious problems with both of these applications. As a totally blind person using the latest version of mountain lion on a standard macbook, I am finding that both iBooks author and iBooks producer are not working with voice over properly. I have an iTunes connect account, I have a book ready to go, but voice over is not speaking all of the text boxes in either iBooks author or iTunes producer to allow me to upload the book. As I am totally blind, i rely totally on voice over to tell me what is on each screen. I can read other peoples books fine both on my iPhone 4s and my iPad3 using voice over, but voice over isn't allowing me to publish my own content. Apple can you please fix the voice over accessibility of both iBooks author and iTunes producer please? At present voice over only speaks parts of each of the different screens. Other apple applications are working well with voice over such as pages and numbers, and of course, most of the inbuilt mac applications are working really well. It's great that totally blind people can use our iPhones and iPads with voice over to read our favourite books which are published from others from the iBooks store, but totally blind people would love to publish our own content as well pretty please.