How to implement a class in console application

A console application is one that runs at a command prompt without a graphical user interface, or at least without the Windows Forms graphical user interface.
When you create a console application from the New Project dialog, you will get the basic
code shown here:
using System;
namespace HelloWorld
{
/// <summary>
/// Summary description for Class1.
/// </summary>

class Class1
{
/// <summary>
/// The main entry point for the application.
/// </summary>
[STAThread]
static void Main(string[] args)
{
//
// TODO: Add code to start application here
//
}
}
}

The using statement at the beginning of the listing indicates that the console application is using the System.dll assembly installed with the Microsoft.NET framework. The System assembly contains the most fundamental elements of the Common Language Runtime. For
now, think of an assembly as an application or DLL, and the using statement as an “include”
in C++ or a “uses” in Delphi.
The namespace construct comes next. Namespaces are a higher level of conceptualization than classes. A namespace is a convenient way to organize elements together and to uniquely identify them. Two separate namespaces can contain the same class. By default, the namespace given to the console application will be the name given to the project in the
New Project dialog.

The three slash marks (///) is a special comment used to support automatic documentation
generation, and the // and /* */ comment styles are supported in C# too. The class definition is provided next. By default, auto-generated code constructs are given the name type number—for example, Class1, where Class is derived from the type of construct, a class, and the number is appended as a suffix to ensure a unique name. You are encouraged to provide a descriptive name for classes.

Inside the basic console application, we have the startup procedure Main. Main is defined as a static member, which means we do not have to have an instance of the enclosing class to call the method. The argument string[] args indicates that Main is passed an array of strings
representing the command line arguments. Finally, note that all constructs have an opening and closing bracket pair, {}, using the same level of block indentation to facilitate readability.