Groups allow you to share citations and files with other people. To create a group you must be in Zotero Online. Groups can be accessed and added through the desktop component, but they cannot be created here.
Create a Group:
There are three types of Zotero groups.
After you create the group, you can invite members by clicking on "Manage Members."
Once in "Manage Members" you can "Send More Invitations" and/or "Update Roles of other members.
You add members by using the email address they signed up for Zotero with. Library/Group members will receive an email from firstname.lastname@example.org
Once members join the group, they will need to sync their Zotero accounts before they see the group in their Zotero library.