You can't! You can only add headers and footers in forms and reports.
For forms:
Open the form in design view. From the View menu, select Page Header/Footer,
or Form Header/Footer (as appropriate).
For reports:
Open the report in design view. The Page Header/Footer will already be
displayed. To display Report Header/Footer, select Report Header/Footer from
the View menu.
Regards,
Graham R Seach
Microsoft Access MVP
Sydney, Australia