Dim s As String

Private Sub Command1_Click()
CommonDialog1.ShowOpen
файл = CommonDialog1.FileName
Open файл For Input As #1
Line Input #1, s
Print s
Close #1
End Sub

Private Sub Command2_Click()
s = s & "!"
End Sub

Private Sub Command3_Click()
CommonDialog1.ShowSave
файл = CommonDialog1.FileName
Open файл For Output As #1
Print #1, s
Print s
Close #1
End Sub