After you've registered for a Zotero account and gotten yourself all set up (see the "Getting Started" tab above), you can create or be added to a Group Library in Zotero.
Creating a Group
- Go to Zotero.org
- Log in (top right corner of the page)
- Go to the "Groups" tab
- Click "Create Group"
Adding people to a Group
- Go to Zotero.org
- Log in (top right corner of the page)
- Go to the "Groups" tab
- Under the name of group you want to add members to, click "Manage members."
- At the bottom of the Manage Members page, click the "Send more invitations" link.
Check out Zotero's Documentation (Groups) for much more information