how to combine a string with date and produce a new string in .net core code example

Example 1: how to append something to a string in c#

string fName = "hello ";    
string lName = "world";    
string Name = string.Concat(fName, lName); 
//or
string firstName = "hello ";    
string lastName = "world";    
string name = firstName + " " + lastName;

Example 2: c# Add or Concatenate Strings In C#

string str1 = "ppp";  
string strRes = str1.Insert(2, "bbb");  
Console.WriteLine(strRes.ToString());