How to Use Zotero Referencing Software

I have downloaded and installed Zotero referencing software. I have managed to get this software working in Windows and with Microsoft Word after a lengthy trial and error session. I have a large library of references which I would like to export but I am not quite sure which file format to use for the export. I would like someone to give a brief explanation for the common file type that you can use to export a list of references from Zotero to Microsoft Word.
