In EndNote Online

• Go to the Collect tab and choose Import References.
• In File: click Choose File button and select file from your computer.
• In Import Option: select PubMed (NLM) from the list.
• In To: select New Group or the appropriate folder.
• Click the Import button.

Look for a direct export option to move citations automatically into EndNote Web.

If no such option is offered, you can always create a text file of the citations then import the text file into EndNote Web. Look for format options such as:

complete reference 

full format

generic bibliographic management software

EndNote Export

RIS format