I’ve self-published a few ebooks myself since April. I learned the process (and continue to learn it), by trial-and-error, and by reading the blogs and message boards about the topic.
However, if you want a more systematic overview of electronic self-publishing, consider looking at David Gaughran’s new book, Let’s Get Digital. The book is an excellent survey of the current state (or lack thereof) the publishing industry and the current state of electronic self-publishing. It also contains a straightforward guide to self-publishing your own ebooks, with success stories from 33 self-published writers, and an exhaustive listing of online ebook-related resources at the end of the book.
I suspect Mr. Gaughran’s biggest challenge will be keeping the book up to date, due to the massive flux in the publishing world right now. (I’ve had something a similar challenge with my The $0.99 Beginner’s Guide To Ubuntu Linux book, given Ubuntu’s six-month release cycle.) Fortunately, nonfiction ebooks have one major advantage over nonfiction paper books – they’re much easier to update.