To access your library from multiple devices, you will need to sync it to EndNote Online. 

1. First, go to EndNote Online, and register an account if you have not already.
2. In your local EndNote library, click on the Library tab, and select Sync.
3. Enter your EndNote Online account credentials.
4. You will be asked if you want to merge your libraries. Syncing your library will combine it with any other EndNote library on your computer. Make sure that you are okay with this before going ahead. 
5. All of the references and groups in your library will be uploaded to EndNote Online. 
6. To access these references from another device, open a new EndNote Library from that device and sync following the above steps. This will download your references to the new device, allowing you to work with your library from there. 

Once you've configured your EndNote 20 desktop library to sync with your online library, you can activate the sync process and check on its status:

1. Click on Sync Status on the top left-hand side of the screen. The sync stats of your library will be displayed.
2. Click on Sync Now in the top right-hand side of the screen, to initiate a refreshed sync status.