How to dynamically add items from different entities to lists in ASP.NET Core MVC

This is my first experience with lists in general and I have kinda complex scenario. I want to add an object of type Story that has a list of Sentences that can be added dynamically. Sentence has a one-to-one relationship with Image and another one-to-one relationship with Audio (that are optional to add). I managed to add the sentences list to the database along with the story object. But I have no idea where to start with the other two entities.

ASP .Net Web App not publishing .cs files and Database

I have a web portal app. I built it in Asp .Net. The app is now ready but when I try to publish it using Visual Studio, I only get the .aspx and .css files. It does not include the .cs files that have all the backend code and functionality, and it does not include the database either. The method I used for publishing the app was:
Right Click my project -> Click on Publish -> Select IIS,FTP,etc -> Select File System and provide Target Path -> Click Save.
It published the app at that targeted location. But, when I open that folder, I can only see the .aspx and .css files and no .cs files, as you can see in the following screenshot.