substr how to obtain???

Menu.Show
   Dim SVR,USR,PWD,DBN As String
   'leggo dal file di testo i parametri per comporre la stringa di connessione al db remoto
   If FileExist ("DBConnParam.txt") = True Then
      Msgbox("File Parametri Connessione Trovato!",progname,cMsgboxYesNo,cMsgboxHand)
        FileOpen (c1,"DBConnParam.txt",cRead ,, cASCII)
        r = FileRead (c1)
       Do Until r = EOF
           Select r
            Case SubString (""&r,1,3)= "SVR"
               SVR = SubString (""&r,3,StrLength (r))
            Msgbox (SVR)
             Case SubString (""&r,0,3)= "USR"
                 USR = SubString (""&r,3,StrLength (r))
            Msgbox (USR)
         Case SubString (""&r,0,3)= "PWD"
                PWD = SubString (""&r,3,StrLength (r))
            Msgbox (PWD)
         Case SubString (""&r,0,3)= "DBN"
                DBN = SubString (""&r,3,StrLength (r))
            Msgbox (DBN)
         End Select
         r = FileRead (c1)
      Loop
   FileClose (c1)


         '      sum = sum + r
         '       r = FileRead (c1)
         '      x = FileGet (c1, 3) 'x value will be of the third number stored in the file
      '      Msgbox(x,"My First Program",cMsgboxYesNo,cMsgboxHand)
         'Loop
            'FileClose (c1)
   Else
     Msgbox("File Parametri Connessione Non Trovato!",progname,cMsgboxYesNo,cMsgboxHand)
   End If
End Sub

""&r

Select SubString (""&r,0,3)
Case "SVR"
    SVR = SubString (""&r,3,StrLength (r)-3)
    Msgbox (SVR)
Case "USR"
    USR = SubString (""&r,3,StrLength (r)-3)
    Msgbox (USR)
Case "PWD"
    PWD = SubString (""&r,3,StrLength (r)-3)
    Msgbox (PWD)
Case "DBN"
    DBN = SubString (""&r,3,StrLength (r)-3)
    Msgbox (DBN)
End Select