If your Zotero application is installed properly, the Zotero's Word plugin should be installed automatically. You should see a Zotero tab above the Word's ribbon area. Click on the Zotero tab, you should see the Zotero toolbar. This Zotero toolbar enables you to insert a new in-text citation in your document conveniently, and the bibliography will be automatically updated to include the cited item.
Clicking the “Add/Edit Bibliography” button in the Zotero toolbar inserts a bibliography at the cursor location.
Zotero will automatically update the bibliography based on the citations in the document.
Simply select items in the center column in Zotero and drag them into any text field. Zotero will automatically create a formatted bibliography for you.
Make sure you set the default export format. Open the Zotero preferences menu and select Export. Set the default export format here.
Or select items in the center column in Zotero, then right-click (or control-click on Macs) to select “Create Bibliography from Selected Item(s)…”. Then select a citation style for your citation/bibliography format and choose to create Bibliography from item, then Copy to Clipboard, then paste it to any text field.