Writing for eBooks is no difference from writing for normal printed books. The ease of which one can write and self-publish an ebook means that there will be many "authors" around. In order to differentiate your creation, it has to stand out and be of good quality. Like all knowledge and skills, ideas and know-hows could be learned from books dedicated to the specific subjects - and in this case, writing.
Below are some books that are geared to the teaching of writing. See if they are suitable for your needs.
