Find an iBook aggregator whose terms and conditions you feel happy with. Apple does not permit a writer to upload her own book. A list of approved aggregators is available at iTunes Connect. Aggregators help authors comply with all Apple's technical standards, and in general market the book and manage its distribution to other e-book retail outlets. Alternatively, a writer can work directly with Apple, in which case she needs to do everything the aggregator does for herself. However, Apple does not guarantee that it will work directly with a writer who follows Apple's requirements, and may still refer her to an aggregator.
Get an International Standard Book Number, otherwise known as the ISBN. An aggregator will assign one to a book, but if you are dealing with Apple direct, you need to apply to the U.S. ISBN Agency for an e-book publisher number. It takes approximately 15 days to process a standard application. At the time of publication, a single ISBN costs $125, and an ISBN plus widget, which allows readers to use "Viewinside" costs $185. If you plan to publish up to 10 titles, it is more cost effective to buy a block of 10 ISBNs for $250.
Convert your manuscript, usually a Word document, into the ePub format. This is a publishing format issued by the International Digital Publishing Forum. Mac users who have iWork '09 already have all the necessary tools in the Pages program that comes as part of the iWork suite. There are a number of free and paid-for services online that will convert documents to the required ePub format. Don't forget to put the cover design for your e-book in ePub format as well.
Ensure your cover illustration and any other graphics material meets the technical standards. The cover should be a vertical rectangle that is 600 pixels in height. It cannot be a greyscale image. The cover must include the book title and the author's name, but it must not include a Web address. The cover design should fall within the PG 13 guidelines and not contain any nudity. (see references 3)
Price your book according to Apple's requirements. Apple prefers to price books in 99 cent increments, so you are encouraged to follow Apple's standard. You can judge an appropriate price for your book by looking at prices for similar titles. You will also need a valid U.S. Tax ID and an account with iTunes that has a valid credit card on file. Your book is now ready for submission.