After installing Zotero, you will be prompted to install Zotero Connector. It is highly recommended that you install this add-on to your browser to ensure seamless downloading of online references to your Zotero programme.
Create a Zotero account in order to use features such as creating a group library and syncing your library across devices. You can find out how to use these features under the Zotero Account (Web) section of this guide.
To register, simply go to this page: https://www.zotero.org/user/register
Do note that the Zotero desktop version has more functionality. The Zotero Web version serves as a backup of your library. Watch this video to see a comparison of differences between the desktop and web library: