When you install Zotero, an add-in should be automatically inserted into Microsoft Word that creates a new Zotero menu at the top. As you write your paper, you can insert in-text references and footnotes that will draw from the citation info in your Zotero library. You can then insert a bibliography of all the sources you've cited, in the style of your choosing.
First, open the Zotero menu in Word, click on Document Preferences, and choose the desired citation style. You can change the citation style here at any point.
To add a citation...
To add a bibliography, click Add/Edit Bibliography from the Zotero menu. You will need to have citations inserted in your document using Zotero for this to work. This should generate a bibliography with the sources you've cited so far. As you continue adding citations, the bibliography should automatically update. If not, you can click the Refresh button in the Zotero menu.
While most of the common citation styles are already in Zotero, the one you want to use may not be. To load a citation style so that you can create bibliographies and citations in that style, follow these steps in the Zotero program on your desktop:
Carlyle Campbell Library
Meredith College
3800 Hillsborough St.
Raleigh, NC 27607
919-760-8532