If you have installed the Google Connector plugin for Chrome or Firefox and open Google Docs, you should see a Zotero menu item.
You will be able to add/edit citations and your bibliography from within the Google Docs environment.
Please note that you will need to have the Zotero desktop open in order for this feature to work.
To add a citation select Add/edit citation.
A red search bar should appear and you can search for your citation and press enter to insert it into the document.
To add a bibliography select Add/edit bibliography and your bibliography will be added to the end of your document.