To use Zotero, you'll need to download two items:
1. The Zotero application
2. A connector that will allow you to save citations to Zotero from your browser
This video from the Georgia State University Library demonstrates how to download and install the Zotero application.
You can use Zotero in Chrome, Firefox, and Safari. Each browser has its own connector, so if you use all three, you'll need to download a connector for each.
A Zotero connector is the tool that allows your browser to communicate with the Zotero application. Using a connector, you can save citations to Zotero directly from your browser.
The Zotero downloads page will automatically detect which browser you're using and give you the correct connector link.
Just follow the prompts to download and install a connector. To troubleshoot, you can use Zotero's installation page.