Registering for a free Zotero account gives you a number of benefits, including the ability to sync your library between computers and the Zotero cloud, participate on the Zotero forums, and create and participate in shared Zotero groups. To create an account:
In order to back up your citations to the Zotero cloud and sync your library between computers, you'll need to set up Zotero Sync with your Zotero.org account.
To set up Sync:
If you use Zotero on more than one computer and want them to stay in sync, repeat this process on each of your computers. Any updates you make on one of your computers will be reflected on the others. This even works to synchronize your library among Windows, Mac and Linux computers. More about Zotero sync
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.
First, set up Zotero sync and synchronize your library.
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.