What is the process that is needed in order to make an ebook? I'm an student from the International Baccalaureate and I need to analyse a case study.
For general purposes, Ebooks are simple websites, contained inside of a predictable folder. This folder is composed mostly of the content of the ebook itself which is the form xhtml and css. The other files are files which declare exactly what contents are in the ebook folder. Each xhtml page, stylesheet, image, font, etc. is listed in one of these files so the folder understands what it is composed of. By following the rules listed on the governing body of the EPUB standard http://idpf.org/ you can write one of these files yourself. The other files can also be written on basically any front end developing software, Dreamweaver, Coda, etc. So, in theory, while it would be tedious, you could create an ebook with just a simple text editor.
That being said, mostly everyone is developing stream-lined way to create EPUBs as an export from a WYSIWYG application, including newer versions of InDesign. This way you would layout the ebook the way you want, with formatting styles for paragraphs, headers, etc. and simply hit an export button and voila, you have your ebook.
I hope this answers your question. :)