Complete your manuscript. This may sound simple, but publishing an unfinished manuscript makes little sense. Make your manuscript as good as it can be before proceeding with self-publishing.
Edit your manuscript --- take your time and be meticulous. Self-publishing removes the editor you'd otherwise have with a publishing house, so you are responsible for ensuring your e-book has as few language errors as possible. You may also want to enlist grammar-savvy family and friends to help you edit your manuscript. Professional freelance editors can provide the final polish to your e-book, and some may also offer formatting services for an additional fee. Although editor rates vary with experience, you can expect to pay around a dollar per page or more to most professional editors.
Choose formats for your e-book. For example, if you want your e-book available for download on the Kindle, it must be in the Kindle format and you'll need to sign up for a publisher account on Amazon. This can be challenging for self-publishers, so consider an umbrella company like Lulu or eBookIt. You can choose to make your e-book available on CD for sale at readings or other book events.
Other formats used often for e-books include Portable Document Format, Rich Text Format, HTML and Microsoft Word.
Purchase an ISBN from R. R. Bowker. The ISBN is a standard number which identifies your book. Booksellers use this number to keep inventory records and libraries use it for identifying their holdings. You must have an ISBN to list your book on Amazon and Barnes and Noble. If you choose to offer a print version of your self-published e-book, you will need a separate ISBN for that. If you choose to self-publish through one of the umbrella publishers, you may be able to save money on your ISBN fee.
Create a cover. Even though your book is electronic, readers will expect a cover. You can use a stock image offered for free from websites which offer them, or you can hire an artist to create the cover for you. Unlike a paperback cover, you will not need a spine and back cover unless you need these for a CD version of the e-book.
Convert your book into the formats you've chosen. If you created your book in Microsoft Word, Microsoft offers an add-on for free that will allow you to convert to PDF format. You can also shift to HTML view within that program. Other word processing programs may have different plug-ins that can be added.