1. Go to www.zotero.org.
2. Click on the red button "Download Now".
3. Download Zotero 5.0 (Mac version is shown; it's also available for Windows and Linux) for the standalone program and the Word plugin.
4. Install the Chrome Connector (or Firefox or Safari) for the browser extension.
5. Create a free online account. This creates a space for you on the Zotero server and allows you to add or access your references from any computer through the Zotero interface.