There is a written tutorial here: http://www.webassist.com/tutorials/Dynamic-Dropdowns-with-Data-Bridge-2-0
and a video tutorial here: https://www.youtube.com/watch?v=M6NRl3l6q7A&t=148s
They are specifically addressing loading a dynamically populated select list with framework builder and AJAX, but the concept is the same for loading any dynamic content via AJAX. Follow the tutorials and see the methodology and then you should be able to abstract how to load just about anything with AJAX and framework builder.