Have you tried Sigil? I just created a book for the Kindle by copying/pasting text from a website serial novel.
Once in Sigil, I did a little cleaning up, chapters, images, etc. and saved as an ePub. From there, I converted to .mobi in Calibre and it looks great. And I'm a beginner!
Sigil is great since it offers both WYSIWYG and code HTML code views. Check it out here on the forum.
