Please read this extensive document from Rice University and view pp. 17 - 21 to learn about using the Word Plug-in to generate in-text citations and full bibliographies.
Video: Zotero - Cite as You Write from Albert S. Cook Library at Towson University. (about 9 minutes) . This is a top pick video tutorial on this topic.
Video: Getting Started with Zotero: Inserting Citations into Word from University of Idaho Library (about 3 minutes)
Video: Zotero Word Processor Plug-In Basics video from Loyola Marymount University Library (about 5 minutes).