Ebooks are digital books that you can publish and sell online. The advantage of publishing an ebook is that, you the author will not spend money in publishing your book and you will never carry your published book on your head to distribute it.
You will not pile up your book somewhere in your room. Your published book will not also tie down your money.
The only challenge about ebook is marketing. Unlike the traditional published paperback book, you will not be able to display your book on a book shelf for people to find it. You can only sell your ebook yourself or through an online ebook store.
One of the ebook stores in Nigeria where you can sell your ebook is okadabooks.com but you must convert your ebook file to epub format.