To transfer a file from Program Content to Dynamic Content, best practice calls for first creating a folder in the Dynamic content tab to place transferred files.  

Create a folder in the Dynamic Content tab.  This folder will keep transferred content organized.

Click the file you would like to copy over to the dynamic content tab.  Click the transfer button seen below in the Program Content tool bar as two yellow folders with green transfer arrows. Within the Transfer Content window, located the file on left within the Program Content area.  Click and drag the file to the desired folder location with the Dynamic Content on the right.  Notice the folder we created named, "Dynamic Content" prior to the transfer to keep the content organized.  Click "Yes" to transfer a copy of the file.

If the file name does not appear within the Dynamic Content tab, click the refresh button seen below. 

Check that all content transferred into the Dynamic Content tab is published.  Like all content, if it is not published, it won't be available for programming use.