Insert();

Insert(); function in C#
It's used to utilized to embed the predefined string at an indicated record number. The record number begins from 0. Subsequent to embeddings the predefined string, it restores another changed string. 
Program

using System;

namespace program
{
    class Program
    {
        static void Main(string[] args)
        {
          string str1 = "";  
          string str2 = str1.Insert(0,"Wellcome");  
          Console.WriteLine(str2);  
          Console.ReadKey();
        }
           
    }
 }

Output
Wellcome