Install MS Word Plugin
To install the MS Word plug in:
When installed the plugin will appear as below on Microsoft Windows:
Generating Citations with MS Word
Note: There is a slight difference with MS Word on Mac as the Cite-O-Matic will appear as its own toolbar.
Referencing in MS Word with Mendeley Desktop
Choose a Citation Style
Click View → Citation Styles → More Styles to search for citation styles on Mendeley Desktop. 
Advanced: The Citation Style Editor
Start editing your own citation styles with the open source Citation Style Editor. To get started we recommend this tutorial.