There is two method to call the Core Template file in Magento
Method 1 : For calling a core template file in .phtml file
I have created a .phtml file named as newfooterchanges.phtml and putted it under the custom folder, means app/design/frontend/default/your_custom_theme/template/custom
<?php echo $this->getLayout()->createBlock('core/template')->setTemplate('custom/newfooterchanges.phtml')->toHtml(); ?> <?php echo $this->getLayout()->createBlock('core/template')->setTemplate('Your_Folder_Name/yourfile.phtml')->toHtml(); ?>
Method 2 : You can call this file in the CMS page by using the admin panel, just navigate to the CMS > Pages and select the page and now use the code below to load the file
{{block type="core/template" template="Your_Folder_Name/yourfile.phtml"}}
You have done and check your CMS page or the custom page.
Hope it helps, Thanks for reading.