[1] Add a controller

Add new file at MvcMovie\Controllers\HelloWorldController.cs:

using Microsoft.AspNetCore.Mvc;
using System.Text.Encodings.Web;

namespace MvcMovie.Controllers;

public class HelloWorldController : Controller
{
    // 
    // GET: /HelloWorld/
    public string Index()
    {
        return "This is my default action...";
    }
    // 
    // GET: /HelloWorld/Welcome/ 
    public string Welcome()
    {
        return "This is the Welcome action method...";
    }
}

[2] Edit controller method

    public string Welcome(string name, int numTimes = 1)
    {
        return HtmlEncoder.Default.Encode($"Hello {name}, NumTimes is: {numTimes}");
    }

REFERENCE:

https://learn.microsoft.com/en-us/aspnet/core/tutorials/first-mvc-app/adding-controller?view=aspnetcore-8.0&tabs=visual-studio-code