How to get mac address in string format(actual format )

If it's just a case of manipulating the string to insert the dashes, then this should work:

        string mac1 = "00114313D165";
        System.Text.StringBuilder sb = new System.Text.StringBuilder(mac1);
        for(int i = sb.Length - 2; i >= 2; i -= 2)
        {
           sb.Insert(i,'-');
        }
        string mac2 = sb.ToString();
        Console.WriteLine(mac2); // 00-11-43-13-D1-65