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
<bib> and </bib> whereby in between the tags you have to put the citekey.
You can only use bib if your reference exists in the biblio reference database of tnl. To do that, go to create content -- biblio and add a reference, which can be anything from book to article to journal, etc. Once you have entered your reference a citekey will automatically be generated (you could also enter one by hand). the automatically generated citekey is just a number. Put this number between bib tags and it will again create an automatically numbered endnote which will contain your reference.
However, entering references one by one is slow, if you have many. There is also a way of doing batch upload of references. You can try here http://www.thenextlayer.org/admin/settings/biblio/import
If you manage your references with endnote, RIS or bibtex you can batch upload into biblio. Make sure you get the import of tags right. If not, go 'recent posts' after upload and you will see all the recently uploaded references and you can tag them so that you will be able to find them later.