Adding script to each page header

I could use some guidance here. I need to know how to go about inserting this on each page of my site. In the head section. Over 9k in pages

<!– Start Alexa Certify Javascript –>
<script type=”text/javascript”>
_atrk_opts = { atrk_acct:”############”, domain:”domain-name.com”,dynamic: true};
(function() { var as = document.createElement(‘script’); as.type = ‘text/javascript’; as.async = true; as.src = “https://somecode.cloudfront.net/atrk.js”; var s = document.getElementsByTagName(‘script’)[0];s.parentNode.insertBefore(as, s); })();
</script>
<noscript></noscript>
<!– End Alexa Certify Javascript –>

Kind regard and thank you.