Answer:
'Harvard system' is a convenient nickname. It is sometimes called the name - date - letter system.
If you are quoting from a book by Jane Doe published in 2002 you give the reference in the next in the form Doe (2002, 91-2). (Here 91-2 refers to the pages). If you quote from (or refer to) more than one publication by Jane Doe from 2002, you would have to add a letter and distinguish between Doe (2002a), Doe (2002b) and Doe (2002c).
Some colleges, publishers and periodicals like a colon between the year and the page numbers, for example Dalton (2000: 44-50), so check the house style sheet for such details.
Obviously, there has to be a proper bibliography (with a key) at the end.
It is also most important that the short forms of works, such as Cuypers (2005) and so on are used consistently throughout the paper or book.
The system is very versatile. For example, you can even anticipate the reference. For example, you say 'As Roe (1998, 56-60) demonstrates, the evidence for this claim is weak'. You might add something like : '(See also Smiles 2004a, 140-2 for further comments on this)'.
One of the enormous advantages of this system is that it greatly reduces the number of endnotes and/or foonotes. Instead, the references are included in the main body of the text, which many find convenient and reader friendly.