Course Files provide central storage on your institution’s Blackboard server for storing content you upload from a local drive.
In your course, you can attach Course Files in areas where attaching files is available, such as content items, interactive tools, and assessments.
Creating a New Content Item
Make sure that you are in the relevant content area.
Create an Item using the Build Content menu:

Give your content item a name and description where appropriate

Click on the Browse My Computer or Browse Content Collection button to add your content as an attachment:

When you are done, click on Submit.
Check any of the options for tracking changes and any date restrictions.

When you are done, click on Submit.  The new file will then be added to the Content Area.