Unable to understand Expand your domain modeling skills - module 2.4.2

Hello developers, I am unable to understand and follow the steps given in this module , I have attached the screenshot of the part where I am facing the challenge particularly I am unable to understand step D , E where this class come from and where should i apply these properties  , If somebody can help me with it or can provide the project they build for the same module for reference 
2 answers

See the below sceenshot.
You can double click the outer most Layout grid of this page to bring up the Popup. (In the screenshot you can see my mouse cursor)​​​​​​


Hi Harshit,
These properties you configure from the Appearance tab of your elements, ex. Containers, data view, etc... 
And add the class Card Cardmetrcis in the Class under common section :