To add a footnote go to menu Insert › Footnote/Endnote and confirm OK. The programme will do the numbering for you. You can even cut a footnote anchor and move it around your text, placing it before or after other footnotes, and footnote numbering will be immediately updated. If you have only just one footnote on the page you might prefer a character* instead of a number.
On the whole it’s best to do without footnotes. You might, however, want to use them to point to further reading or arguments by other authors which you don’t want to deal with directly in your main text because that would interrupt the flow of reading. In this case you might want to use endnotes instead of footnotes.
For bibliographical purposes you don’t really need footnotes. Use the Harvard notation instead: (Wilson 2005 : 27), (Wilson 2005a : 27) in case you are referring to several of his writings of the year 2005 and (Wilson et al. 2005 : 27) in case you are referring to a work co-authored by Wilson. In other words limit yourself to author’s name, date of publication and page number directly inside your text. Reserve all other details for your bibliography at the end of your paper (see section 23).
The Harvard Notation without recourse to footnotes is by the way not necessarily the most suitable in all circumstances. In university circles, where arguments often follow the flow of quoted authors, it does seem appropriate. But in other contexts these brackets right in the middle of your text could be quite distracting. In this case footnotes are justified.
Footnotes like all other elements have their own individual paragraph style based on Default.
You can jump from one footnote to the next using the Up and Down arrow keys without having to return to your text in between. This facilitates an overall brush-up of all your footnotes in one go.
* Umberto Eco’s ‘How to Write a Thesis’ is a wonderfully enjoyable guide for anyone wishing to embark on such a journey. Unfortunately this work by the great philosopher and writer doesn’t seem to have been translated into English.