PHP meta tags in CMS posts.

I took a course on PHP which consisted on a lesson on building a CMS 
(blog) from scratch.

While the course is complete, there are gaps. For instance, no comments 
section and no field for metatags for entries.

The instructor said the course is about learning PHP, not actually using 
what we make. I want to refine the CMS and use it.

I would also like search engine crawlers to correctly index entries.

Am looking at hacks / PHP tools to help correctly identify entries for 
web search indexing.

The site itself has metatags, but each entry must also have tags. So if 
you have a site about cars, then each entry can be about particular car, 
like fiat, jeep, convertible and so on.

Normally, a CMS has a field entry for metatags, but since this is not 
covered in the lesson, I wonder if there are tools in PHP to facilitate...?

One hack is to perhaps embed metatags for each blog / cms entry.

Thoughts?

-I-