Adding 7 days to a date using macro

Hi!

It would be really great if you could help me with my macro that I am trying to create for my spreadsheet.

Basically it's to make my content management easier.

I have made a button and assigned a macro to it. At the moment the button creates a new column and makes it the right size etc.

Sub new_week()
'
' new_week Makro
' Makro am 25.02.2009 von  rs aufgezeichnet
'

'
    Columns("B:B").Select
    Selection.Insert Shift:=xlToRight
    Selection.ColumnWidth = 10.71
    Range("C21:C30").Select
    Selection.Copy
    Range("B21").Select
    ActiveSheet.Paste
    Range("B21").Select
    Application.CutCopyMode = False
    Selection.ClearContents
    Range("B22").Select
    Selection.ClearContents
    Range("B23").Select
    Selection.ClearContents
    Range("B24").Select
    Selection.ClearContents
    Selection.ClearContents
    Range("B25").Select
    Selection.ClearContents
    Range("B26").Select
    Selection.ClearContents
    Range("B27").Select
    Selection.ClearContents
    Range("B28").Select
    Selection.ClearContents
    Range("A15").Select
    ActiveCell.FormulaR1C1 = "New week added!"
    Range("A13").Select
End Sub

However what I really want is for the newly created cell to take the date from the cell next to it and add 7 days to it. For example: 04.01.-10.01. (is the original date) and 11.01.-18.01. (would be the new date)

Any kind of workaround(other way of formatting the date) or new logical process you have for doing what I want would be really great!

P.S im using Excel 2000 (German version)

Thanks in advance!

-Ninjao