To import a style to Zotero:
As of 2015, there is only two bibliographic styles (Chicago and APA) for which Zotero provides the option to do an annnotated bibliography.
1. Go to the Zotero Style Repository and do a search for "annotated" to find Chicago Manual of Style (Annotated Bibliography) and APA (Annotated Bibliography), and install it.
2. When adding/edition citation info, use the "Extra" field (found way down at the bottom of the Info tab in the right column) to add your annotations.
3. When creating your bibliography, choose Chicago Manual of Style (Annotated Bibliography) or APA (Annotated Bibligraphy) as your style and Copy to Clipboard as your output format.
4. Paste your bibliography into a Word document.
It's easy to create a bibliography from your Zotero library.
Select the references or collections you want to include. Hold the control key and click to select multiple items. Right-click one of the selected items and choose Create Bibliography. Choose the bibliographic style you want, and select the output format: Save as RTF or HTML, copy to clipboard or print. (The RTF file format is compatible with all word processors.)
Or you can just drag and drop references from Zotero into your document and they will turn into fully formatted citations. This works with any word processor including Google Docs. Change the default style under Preferences on the "gear" menu.
The word processing plugin adds a Zotero toolbar to your word processor that allows you to add formatted citations to your document while you write and then create a formatted list of references from those citations.
To add a citation, click the first button ("Insert Citation") on the toolbar. Select the reference you want to cite and click OK. Zotero will add the citation at your cursor.
At the end of your paper, click the third button ("Insert Bibliography"). Your bibliography will appear, and new citations will be added automatically. Change bibliographic styles with the last button on the toolbar ("Set Doc Prefs").
If you're using MS Word 2016 for Mac, the Zotero Toolbar is found in the Add Ons tab
If you're using MS Word 2011 for Mac, you'll need to make your Zotero toolbar visible.
If you are using MS Word 2008 for Mac, then Zotero is installed in the script menu (to the right of the Help menu at the top of the screen)