EndNote Online is a web-based, version of EndNote. Entries created in EndNote Desktop can be easily moved to EndNote Online and vice versa. See EndNote Online Quick Guide. It is necessary to enable syncing and sharing EndNote libraries. It is easier to use the desktop version as your working EndNote Library.
To sync you need to create an EndNote Online account.
Click Configure sync and fill in your details to create an EndNote Online Account.
Once you have a login, you can use the Sign In link to connect or connect directly to EndNote online at http://www.endnote.com
Synchronize EndNote Desktop and Online Libraries