Start a new workbook.
Set up everything you want--headers/footers/layout...
Save it as book.xlt in your XLStart folder.

Then excel will use that when you create a new workbook by clicking on the new
icon on the standard toolbar.

If you want the same thing when you add a new worksheet to an existing workbook,
save another workbook (probably a single sheet???) in that same XLStart
folder--but name it Sheet.xlt.