Calibre is a free ebook management program that also creates ebooks.
As noted in the comments, professional level ebooks require some degree of hand-coding to display properly on different devices.
If you want to create an ebook using Calibre, here are links to the Calibre web site which you might want to click on and read the information contained therein.
- A step-by-step guide on converting HTML and Microsoft Word formats using calibre.
- Another step-by-step guide on creating ePub files starting from OpenOffice/Word.
- An in-depth understanding of how conversion works in Calibre
- Calibre tips and tricks Since calibre 2.4, released on 25 September 2014, calibre has added a selection of different cover designs with customizable fonts, font sizes and color schemes.