To add files to your content boxes:
To embed a video:
The embed code for the video below was taking from the YouTube page that hosted the video. Here it is:
<iframe width="560" height="315" src="https://www.youtube.com/embed/LdQeaDN9Qic" frameborder="0" allowfullscreen></iframe>
You can add a text box for anything you want to add that you feel might be helpful.