By calling  Sort() and Reverse()  methods we can sort the 
elements in descending order.

int[] arr = new int[4];
        arr[0] = 22;
        arr[1] = 33;
        arr[2] = 11;
        arr[3] = 44;
        Array.Sort(arr);//First sort the array in accending 
order
        Array.Reverse(arr);//then do reverse of array for 
descending order
        foreach (int a in arr)
        {
            Response.Write(a+"--");
        }