Cesium fits in box when setting up props

I created a scene by looking at sandcastle examples in Cesium. I am comparing two 3d models historically with the scene I created. I’m using the Cesium demo version as I don’t do business commercially. I want to add a toolbar on both sides of the scene that indicates where and what date the models belong to. So in the demo version, can we add boxes with information or functionality to the part of the scene we want?
Can you explain in detail how to do it? i’m new at this job
thanks in advance
Example of my application:
Cesium Sandcastle