How can I add another bubble to our play and volunteer page when it was built with HTML

Hello,

I am looking to add another bubble to this page https://volokids.org/play and https://volokids.org/volunteer. However, when we had someone build this page it was built with HTML post grid widget unlike the rest of our site that is drag and drop eliminator. Please guide me on how I can add another page into this. The page is created, but looking to add a navigation to that page bubble on each of these pages. Thanks so much