You can synchronize your library in EndNote X6 or later with your library in EndNote online. The Sync process automatically synchronizes both sets of references so that an exact match exists in both EndNote desktop and EndNote online.
In EndNote (Desktop) click the Sync button that appears in the toolbar or go to Tools and select Sync. If you do not have an EndNote Web account you will be prompted to create one.
More information on syncing your accounts can be found at: http://endnote.com/kb/122170 by searching using the term “sync”.