Need to insert 468 x 60 banner in twenty eleven theme

start by creating a child theme of Twenty Eleven https://codex.www.ads-software.com/Child_Themes (if you haven’t already).

then save a copy of header.php into your child theme and edit it, and replace the section from:

<?php
				// Has the text been hidden?

to (both inclusive):

<?php get_search_form(); ?>
			<?php endif; ?>

with your adsense code; you will need to wrap the adsense code into a div with a css class for easier formatting, and add the corresponding new styles to style.css of your child theme.

hi mate ur tip is very much useful for me… I need to add advertisement like 728 * 90 to the top of page. Visit technorati.com for eg. Can u help me??