I'm not sure what you mean, but try this.
If you want done on the desktop
Code:
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
My.Computer.FileSystem.WriteAllText(My.Computer.FileSystem.SpecialDirectories.Desktop & "\NameOfFile.txt", TextBox1.Text , True)
If you want done in the program directory:
Code:
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
My.Computer.FileSystem.WriteAllText( "\NameOfFile.txt", TextBox1.Text , True)