It is important that you do not only reference at the end of your assignment, alphabetising the reference list by the authors surname if referencing in the Harvard style, but that you include an in text citation to indicate the point at which you have paraphrased, summarised or quoted another persons work. This indicates to your reader that you have read widely and they can find the work you have used with ease.
If you use a different referencing system, other than Harvard on your course, you may find that you are expected to include numbers or footnotes instead of the in text citation described above. See Cite Them Right Online for full details including referencing expectations and examples for the referencing system used on your course.
See the document below to support you to decode your references in an assignment in the Harvard Style.