Custom Google Search

Login to the appropriate Google account and click the LINK to set up a new custom search.
Enter the site to be searched, give the search engine a name if more than one is required and then click on the "Create" button.
Click on the "Control Panel" button and then click "Look and feel" in the sidebar.
Select the "Compact&qut; layout and then click the "Save & Get Code" button.
Copy the code and paste it into a code editor or TextEdit.app in plain text mode and it will look like this …
<script>
(function() {
var cx = '001230818718971564805:hzinzpx8zxo';
var gcse = document.createElement('script');
gcse.type = 'text/javascript';
gcse.async = true;
gcse.src = 'https://cse.google.com/cse.js?cx=' + cx;
var s = document.getElementsByTagName('script')[0];
s.parentNode.insertBefore(gcse, s);
})();
</script>
<gcse:search></gcse:search>
Copy the code marked in red and paste it into the ID box in the widget settings.
Blog & Podcast
If the website includes a blog or podcast, a separate search engine should be set up specifically for it. Enter it as …
domain-name.com/blog/
… where "blog" is the name of the directory containing the blog or podcast and give the search engine a name such as "blog" or "podcast".
Location
Rather than have the search box on every page of the site, it's better to have it on a page on its own and link to this page with a small button link located on every page of the site.