Adding Portfolio Items to a menu

Hi everyone, I hope someone can help. I’m using the free version of Pinnacle and in the sample content there is a sub page titled ‘Single Portfolio Post’ under the main menu item titled ‘Portfolio’. I am trying to add new Portfolio sub pages based on this example but can’t find the correct starting and whether it’s a ‘page’ or a ‘post’.

In the menu settings the sample page is described as a Porfolio Item but when I create new Portfolio items they do not appear as new items that can be added to the menu – as either a page or a post.

I hope this all makes sesnse and really hope there’s a simple answer! Thanks.