Visual Basic 2010 (Console) Guide
Writing Text Files

Writing to a text file is a very similar process to reading. The main difference is that sometimes we will want to overwrite the contents of a file, sometimes we will want to append information to it.

Append All Text/Write All Text

Dim path As String = "C:\q.txt"
Dim strText As String = "Some text to add to a file"
File.AppendAllText(path, strText)
Console.WriteLine("Appended text to file")
Console.ReadLine()

If the file specified in the first line does not exist, it will be created. The alternative to this is to use the WriteAllText() method.

Writing A Line At A Time

In the same way that we can use a streamreader to read the file, we can use a streamwriter to write one.

Dim path As String = "C:\q.txt"
Dim sw As StreamWriter = New StreamWriter(path)
Dim input As String
Console.Write("Enter a name for the file or end to quit")
input = Console.ReadLine()
While (input <> "end")
   sw.WriteLine(input)
   Console.Write("Enter another name for the file or end to quit")
   input = Console.ReadLine()
End While
Console.WriteLine("Finished writing the file")
sw.Close()
Console.ReadLine()

There are quite a few additional techniques that you might use for writing to text files. The MSDN for Visual Basic has fairly good explanations and examples on the topic.