If you are used to complex text editing programs such as MS Word or Open Office, you will probably enjoy the Footnote and Biblio functions. In your text in a book page (but also other content types such as Research Journal or 'story'), you can us the fn tag <fn>and what you write in between the tags will appear as an automatically numbered footnote, but don't forget the end tag </fn>
Almost analogue to that works the bib tag. If you want to refer from within your text to a bibliographic reference, use