'Ordner (oder ähnlich)
Dim docpath As String = My.Computer.FileSystem.SpecialDirectories.MyDocuments
 
'File
Dim file As String = IO.Path.Combine(docpath, "MyTextSave.txt")
 
Dim text As String = TextBox1.text
 
'Speichern
My.Computer.FileSystem.WriteAllText(file, Text, False)