call another html page not working

@kvanaraj,

This is a choice of absolute or relative links. I prefer absolute links because no matter where the link appears it will always work where as a relative link will only work based on the location of the page (if you use relative link in sub directory it will not work).

I would make your link like this:
Create a PHP variable in the html file so that you only have to change the site url once through the file (You could also do an required or include file of variables)
<?php $url = 'https://www.yourwebsite.com/'; ?>

Then down in your html page
<li><a href="<?php echo $url; ?>edu.html">Education</a></li>