exclude adsense on certain pages

I would use some WordPress conditional tags. You can check if you are on a certain page or on a sub page.

so i think i need to use something like this

<?php if( !is_page( array('Privacy Policy', 'Contact', 'About', 'etc') ) ) : ?>
ADSENSE CODE HERE
<?php endif; ?>

where should this go?

you add adsense code with an plugin or manualy in the source code of your header.php file ??

the code is in my header.php

it`s okay in header but you must use statment is_page( array( name of the pages where adsese will be display)){ addsense code }