CustomWebView : An extended form of Web Viewer

Hello!
I was trying to use the Custom Web View extension. I saw the reply https://community.appinventor.mit.edu/t/customwebview-an-extended-form-of-web-viewer/9934/3 saying that we have to add both the web view component and the Custom Web View. So that is what I did.


Also, no blocks were showing.
But I found where the blocks were hiding.


Can someone please show how to use the Custom Web View extension?