Adding js in Magento Header

I assumed the project root folder is in /public_html/magento/
Copy the js file into:

/public_html/magento/js/yourSubFolder

Tell about this to :

/public_html/magento/app/design/frontend/base/default/layout/page.xml

add this line to

 <block type=”page/html_head” name=”head” as=”head”>  

section

<action method=”addJs”><script>nhdGallery/scripts.js</script></action>