In order to have the full functionality of X9, you should always create and sync an Endnote Online account.
The EndNote Online account:
Need more in-depth help with EndNote Online or EndNote X8? Simply contact the expert for your college.
If you are an undergraduate, contact the librarian who initially taught you EndNote, or the expert for the college you are majoring in.
EndNote X9 allows you to collect, organize and store citations on your desktop and sync with your cloud account to keep your library current.
You can comment on pdfs and search those comments later
Getting Started Guides
5-6 Minute Overviews for Mac and Windows
NOTE:
The library recommends searching the actual databases and NOT using the EndNote interface.
Short Course Webinar Recording (25 min)
Although this is for Windows computers, Macs should function very similarly.