When you install the Zotero software to your computer, it comes with a plugin for Word.This plugin will allow you to add references directly to your papers as you're writing them.
Just click the Add/Edit Citation button to get started.
For more detailed information on updating and editing your citations and bibliographies, check out this guide.
When you install the Zotero browser connector for Chrome or Firefox, it also installs a Zotero menu for Google Docs. This menu will allow you to add citations to your papers as you're writing them.
For more information about how to use Google Docs to add your Zotero citations, view this guide.