There are several reasons why referencing is important.
You should get used to keeping track of all your sources (books, journal articles, websites) and learn how to cite and reference them properly. Use this guide to help.
This is a very useful tool within Microsoft Word and is worth getting familiar with as soon as you start writing your first assignment.
In-text citation
Along the top of your Word document you will see tab called References (you may be familiar with using this to add footnotes). To add an in-text citation, put your cursor at the point where you want your reference to appear. Click on References and choose Harvard. Select Insert Citation. Choose Add New Source. Choose the type of source that you are citing - book, journal article, web-site etc. Then fill in the details. Once you have saved your citation, the information will be available for you to use again.
Bibliography / Reference List
Once you have added your citations, you can create a bibliography with that information. Put the cursor where you want the bibliography to go, then select References and choose a format. Then click on Bibliography and click on Insert Bibliography.
Adding new citations
If you add new citations to your document, you can update your bibliography by right clicking anywhere in your list and selecting Update Field.