Html goes in the html pafe, the div's are put into the html, the css code can either be put in a seperate style sheet *.css and referenced in the html by coding:
The phpbb code won't let me put into the link tag:
link href="whatever.css" rel="stylesheet" type="text/css"
Code:
<link>
Or you can code the css within the page: eg.
Code:
<style>
.content{color: red;}
a {color: blue;}
</style>
For this code, the .content div in the html
The phpbb code won't let me put this bit within the div tag
div class="content"
Code:
<div>Whatever the content has to be</div>
The way you're describing what you're doing, just make up the *.css file, then make a template up including navigation. When you're ready, shove the content in and then replicate the page as you need to. That sounds like the easiest way.
the /folername depends on how your server is set up. Try putting an index.htm or index.html within that folder, it should then go to that page when you do the whatever.com/folder and hit enter.
Good luck!