In subsequent sections, we will look at using Plans (previously known as 'Planner') in more detail, but to quickly add resources to your course you will notice an “Add” button in the upper right-hand corner in the Course Overview page. It is here that you can quickly add a folder, file, task, assignment, test or other activities. By selecting 'show all', you will see all resources and activities available.  

screenshot quick add

Alternatively, you can add course resources directly in 'Resources' or use 'Plans' which is the recommended way as it allows teachers to align course material with standards/learning objectives.