Next you need to create a Zotero account in order to sync your citations across computers and to be able to access your citations on computers that do not have Zotero installed. You can also use your Zotero account to share your citations with others.
Zotero's Groups feature allows you to share references with other Zotero users online. It's a great way to work on collaborative research projects.
You now have two sections in your Zotero collections pane: My Library and Group Libraries.
Personal and group libraries are entirely separate, and changes made to items in one library do not affect the other. You can drag items back and forth libraries to copy items.