Setting up an EndNote Online Library and Synchronising this with your EndNote Desktop Library:
You will need to set up Synchronisation details in EndNote Desktop Preferences.
Only one EndNote Desktop Library can be synchronised with your EndNote Online Library at a time. Synchronisation can be used to combine multiple EndNote Desktop Libraries. The combined set of references will be in the last library synchronised. Libraries can be synchronized at any time by clicking on the Sync button on the EndNote Desktop toolbar.
You can control how your EndNote libraries are synchronized by going to the Edit menu in your EndNote Desktop Library and clicking on Preferences.
Click on Sync in the Preferences dialog box and complete the form:
Note! If you have not already set up an EndNote Online Library you can click on the Enable Sync button and set up an EndNote Online Library.
For more information see the EndNote page Library Sharing.