If a work has an editor or a translator as well as an author you will need to include both in your reference. Start your reference with the author as usual and then include the editor or the translator with the publication information.
To use a footnote, put a superscript number into your text and then the footnote at the bottom of the page.
Format:
Author, Title (edition, Editor (ed) OR Translator (tr), Publisher | year) page number.
Example:
K Zweigert and H Kötz, An Introduction to Comparative Law (Tony Weir tr, 3rd edn, OUP 1998) 66
The only difference is the author is now listed surname first and you do not include page numbers.
Format:
Author, Title (edition, Editor (ed) OR Translator (tr), Publisher | year)
Example:
Zweigert K and H Kötz, An Introduction to Comparative Law (Tony Weir tr, 3rd edn, OUP 1998)