Zotero runs as a separate program on your computer.
You can install Zotero Connector so it works with Firefox, Chrome and Safari.
Download and install Zotero just as you would any other program. You will also need to install the Connectors to allow your browser to save items to your Zotero library.
Connectors allow your web browser to save citations to your Zotero library.
Go to the Zotero download page and install the connector for your browser. It will automatically select the connector to install based on the browser you're using.
Each browser has its own version of the Zotero Connector, so if you use multiple browsers you'll need to install connectors for each one.
To begin using Zotero, download and install the application and browser connector. Both are available for download here. Zotero detects the type of computer and browser you are using to automatically download the correct Zotero tools.
1) The Zotero application enables you to manage your citations from your computer (and off line).
2) The Browser "Connector" enables you to download citation information directly from your web browser when you are online. It syncs with the Zotero application (installed on your computer) and also if you choose to create a web login.
3) Register for a free Zotero account. It is free and will enable you to manage your citations while online. Look for the Register link in the top right corner of Zotero web pages. This web account can be set up to sync with the Zotero desktop application.