Retain Formula when Input is made

Hi,

I'm trying to make a two-in one cell, maybe that's a bad thing, but that document is edited by many people and they are messing formulas all the time

I searched the forum and found one thread with this code:

Private Sub Worksheet_Change(ByVal Target As Excel.Range)

With Target
    If .Address(False, False) = "B1" Then
        If IsEmpty(.Value) Then
            Application.EnableEvents = False
            .Formula = "=IF(B1="""";"""";B1+1)"
            Application.EnableEvents = True
        End If
    End If
End With

End Sub

but I can't seem to get it to work for me. Example what I am looking for: if you input 2012 in "B1" it should give it to you as "2012 y. actual". The same would go with C1, D1 and so forth. By the way, where should I input this code, in microsoft Excel Objects tab in "Sheet1 (Sheet 1)" or create a "module"?

Thank you for your help.