After you have created a resource Item, you can add it to your Assessment via the Activity Builder in the Author Site.
To add a resource Item to an Activity:
Create a new Activity in the Author site, then go to the Navigation / Control Settings panel. You will see the Resource Item option.
Figure 1: The Navigation/Control Settings panel in the Activity Builder
Clicking the Select button will open the Item modal window, where you can search and select the resource Item that you want to add to the Activity.
Important: Items may be created as Features to include passages, files, audio and video. Note that Items with Questions should not be used as a resource Item. If you choose an Item with Questions as resource Item, the Question widgets will be removed when displayed in the assessment resource panel. See Figure 3 for more details about the resource panel.

After selecting the resource Item, you will be able to view it in the Assessment Preview tab.


Figure 3: The Assessment player preview
For more on the resource panel, see Adding Resources to Questions and Features.