List string to file csharp

                
                        string[] lines = { "First line", "Second line", "Third line" };
System.IO.File.WriteAllLines(@"C:\Users\Public\TestFolder\WriteLines.txt", lines);
lines = { "Fourth line", "Fith line" };
System.IO.File.AppendAllLines(@"C:\Users\Public\TestFolder\WriteLines.txt", lines);