If you want to tailor your Resource Center content to only allow it to be viewed by certain users, you'll first need to create a folder using the New Folder button in the Materials section. Please note that this folder cannot be in the Resource Center or in another folder.
Once you've created the folder, open the folder and click on its name in the top.
You will then be able to assign the folder to specific Groups, Courses, and Learning Paths using the tabs at the top.
After your content has been assigned, Learners will be able to see the folder and its content in the Resource Center area only if they are enrolled what you specified.