CSS Virgin --- Need some help

I'm using CSS for the first time. Building a site with multiple pages.

So my template has nav bar on the main page with page1.html, page 2.html, etc.

There should be some way to only change the names of those pages once, and I can't find where to do that.

I've looked in layout.css.

B/c I'm a neanderthal, I would normally just save as/rename each page and edit in notepad. Surely the benefit of using css is being able to change all menu items for all pages only once.

Your help greatly appreciated!

Edit:

In the folder I have a layout.css and a colors.css file. Neither of these have what I need. Am I missing a file?

On the index.html file I have:

<!-- \/ Set of mini links \/ -->
<div class="minilinks">
<a href="index.html">Home</a> |
<a href="page1.html">Page1</a> |
<a href="page2.html">Page2</a> |
<a href="page3.html">Page3</a> |
<a href="page4.html">Page4</a> |
<a href="page5.html">Page5</a>
</div>
<!-- /\ Set of mini links /\ -->

Similar thing nearer the top of index.html for the top/main nav bar. Shouldn't I be able to change that once somewhere so any future updating would apply to all sub-pages?

Can't move forward 'til I figure this ...
so any help appreciated.