Excel 2007 :: Declaring Worksheet And Range As Variables

Using Excel 2007, I'm trying to figure out (and not succeeding!) on how to declare worksheet and range - in order to:

input a formula to cell xfd1, then copy down to xfd2:xfd100 - and here's what I've been playing about with

Code:
Sub filldownxfd()
Dim src As Range, out As Range, wks As Worksheet
Dim sRangeName As String
Workbooks.Item(1).Sheets.Item ("Sheet1")
Dim example As Range
Set example = Range("xfd2:xfd100")

[code]....