New Content not showing

I don't think I understand how this works. Under 'Choose the content area you wish to edit below', if there is no content, there is also no 'Add Content' button. However, if there already is content, the 'Add Content' button shows up ??? I want to add content where there is none so why wouldn't it show up? So I end up selecting on the left hand bar a listing which shows a number indicating how many content boxes it has. I select 'Add Content' and scroll to select the page for which I want to add content. I go ahead and add it to the 'Contact Us' page (which has a contact form already) and I'm expecting a Pod to show up with my new content, but nothing shows up.

Please, give me some direction on this. What am I missing? This is the page to which I want to add more content to, below the form in a new pod.

contactus.php

thank you.