int [] [] myJaggedArray = new int [3][];

Declaration of inner arrays: 
 
 myJaggedArray[0] = new int[5] ;   // First inner array will be of length 5.
 myJaggedArray[1] = new int[4] ;  // Second inner array will be of length 4.
 myJaggedArray[2] = new int[3] ;   // Third inner array will be of length 3.

Now to access third element of second row we write:

  int value = myJaggedArray[1][2];

int[][] jagged = new int[3][];
            jagged[0] = new int[2];
            jagged[1] = new int[3];
            jagged[2] = new int[2];

            int i = 0;
            for (i = 0; i < 2; i++)
                jagged[0][i] = i;
            for (i = 0; i < 3; i++)
                jagged[1][i] = i;
            for (i = 0; i < 2; i++)
                jagged[2][i] = i;

            Console.WriteLine("displaying first array");
            for (i = 0; i < 2; i++)
                Console.Write(jagged[0][i] + " ");

            Console.WriteLine();

            Console.WriteLine("displaying second array");
            for (i = 0; i < 3; i++)
                Console.Write(jagged[1][i] + " ");

            Console.WriteLine();

            Console.WriteLine("displaying third array");
            for (i = 0; i < 2; i++)
                Console.Write(jagged[2][i] + " ");

            Console.WriteLine();

using System;
public class MyArrayclass
{
 public static void Main()
 {
  int [][]arr=new int[4][];
  arr[0]=new int[3];
  arr[1]=new int[2];
  arr[2]=new int[5];
  arr[3]=new int[4];

  Console.WriteLine("Enter the numbers for Jagged Array");

  for(int i=0 ; i < arr.Length ; i++)
  {
   for(int x=0 ; x < arr[i].Length ; x++)
   {
    String st= Console.ReadLine();
    int num=Int32.Parse(st);
    arr[i][x]=num;
   }
  }
  
  Console.WriteLine("");
  Console.WriteLine("Printing the Elemnts");

  for(int x=0 ; x < arr.Length ; x++)
  {
   for(int y=0 ; y < arr[x].Length ; y++)
   {
    Console.Write(arr[x][y]);
    Console.Write("\0"); 
   }
   Console.WriteLine("");
  }
 }
}