Acquire an International Standard Book Number, better known as the ISBN, for the book you intend to publish. This works as an identification number for any book sold in bookstores and even a self-published book sold in Apple's iBookstore. Getting an ISBN can be conveniently done online, and this requires paying a non-refundable fee. The amount you must pay is indicated on the application form. Processing time is about 15 business days.
Proofread your work, then convert the book file into ePub format. This is the required format for any book being published for the iPad. If you can do it on your own, you may manually convert the file using a series of XML and xHTML files grouped together into a zip file. You can also use programs like Adobe InDesign and Calibre for the conversion. You need an Intel-based Mac running in an OS 10.5 or better, along some reasonable technical requirements, to produce the required ePub file.
If you find it more practical and convenient, you may choose to work with an Apple-approved aggregator. This is a company that has a partnership arrangement with Apple. It acts as an agency and production firm to provide all your publishing requirements for Apple. Most aggregators can also assist you in acquiring an ISBN and they usually offer services that may help you keep track of your earnings at the iBookstore as well.
Get a U.S. tax identification number from the Internal Revenue Service (IRS), if you don't have one yet. Non-U.S. authors can apply for one online through the IRS website.
Register for an iTunes Store account by creating an Apple ID and a password. This ID is the one used when signing in to the iTunes Store. This process is very similar to creating a new email address. You will also be prompted for your credit card information.
Upload your ePub file to the test server at the ePub Check website. This allows you to check if your file's conversion process is successful and if it meets Apple's criteria. If you have an aggregator, this means you have a prior arrangement of the more specific steps you need to complete for the requirements. In any case, they are responsible for providing you a properly converted ePub file according to Apple's criteria.
Go to the iTunes Connect webpage, then select "Books." You will be required to provide your personal information as part of the iBooks application process. Follow the application wizard until you are prompted to upload your book's ePub file. Apple will review your application. Within 24 hours, you will be notified via email whether your submission has been accepted or not.