It looks like you're using Internet Explorer 11 or older. This website works best with modern browsers such as the latest versions of Chrome, Firefox, Safari, and Edge. If you continue with this browser, you may see unexpected results.
Zotero is a free citation manager. This page offers information that will help you create and build a Zotero library, create and use groups to collaborate, and use Zotero to add properly formatted citations to your papers.