In any piece of academic work you must acknowledge, with a reference, work that has been done by others or work that has previously been published. With the Harvard System you reference as you go through your assignment.
Footnotes appear at the bottom of the page.
Endnotes appear at the end of a piece work and are usually listed simply under notes. The only difference between using the footnotes and the endnotes system is the position of the reference notes. References are placed either at the foot of tile relevant page, or all together at the end of the assignment. Whichever system you use, choose the one you find the easiest and be consistent throughout your assignment. If you refer to any form of publication put the author's name and the year it was published.