If there is no author listed, use the editor or the translator in place of the author, adding (ed) or (tr) as appropriate. If there are multiple editors use (eds) or (trs) for multiple translators.
To use a footnote, put a superscript number into your text and then the footnote at the bottom of the page.
Format:
Editor (ed) OR Translator (tr), Title (edition, Publisher Year) page number.
Example:
12 Jeremy Horder (ed), Oxford Essays in Jurisprudence: Fourth Series (OUP 2000) 146.
The only difference is the author is now listed surname first and you do not include page numbers.
Format:
Editor (ed) OR Translator (tr), Title (edition, Publisher Year) page number.
Example:
Grevling K (ed), Blackstone’s Statutes on Evidence (Blackstone’s Statutes, 17th edn, OUP 2023)
Birks P and G McLeod (trs), The Institutes of Justinian (Duckworth 1987)