EndNote is a software program that allows you to store and manage your references and images. EndNote will format your references in whatever style you choose -- APA, Vancouver, Chicago Manual of Style, etc. EndNote works with word processing software to allow you to insert citations directly into your paper, building your bibliography as you insert your citations. You can import references into EndNote from many online databases.
EndNote X7 introduced a new sharing mode and EndNote X8 and X9 expand on it:
To sync go to TOOLS>SYNC or use the Sync Button.
Once the library is synced, go to FILE>SHARE and enter the email of users you wish to invite to share your library or use the Share Button. They will receive an email and instructions. All users must be running X7 or X8. Use HELP>CHECK FOR UPDATES to confirm you are running the latest version of EndNote.