In which cases you use override and new base?

Question

using System;

namespace CareerRideTest
{    
  class A
  {    
    public A()
    {
      Console.WriteLine("I am in A");
    }
  }

  class B : A
  {
    public B()
    {
      Console.WriteLine("I am in B");
    }
  }

  class C : B
  {
    static C()
    {
      Console.WriteLine("I am in Static C");
    }
    public C()
    {
      Console.WriteLine("I am in C");
    }
  }    

  class MainClass
  {
    static void Main(string[] args)
    {
      C obj = new C();    
      Console.ReadKey();    
    }
  }    
}