By default, EndNote places references into the Unfiled group. You can create up to 5,000 groups to organize your citations in any way that works for you.
Creating New Groups
Click on the Organize tab at the top of the EndNote Basic screen. This opens the Manage My Groups Screen.
Click New group. Type in the name for the new group and click okay
Adding Citations to Groups
All of the citations that you have added to your collection can be found in the My References tab.
To file a newly imported citation(s) you will need to check the box next to the reference(s) and then click on the Add to Group pull-down arrow. From there you can select the group you would like these citations to be placed in.