There are actually a couple of ways to do this.
you could use the page list block to generate this information.
you could use the 'faq' block from the Market Place to do something like this or
You can do it via the wysiwyg page editor when editing your directory page.
We did something similar for a client here:
http://www.glorioustravels.com/indian-tours/...
This is a list of tours. Each tour has it's own page explaining the details of the tour. This page was created using the WYSIWYG editor. pretty simple really, which is the power of C5

Remo Laubacher has several useful tutorials on his blog that were extremely useful to me when I was getting started:http://www.codeblog.ch/category/concrete5/...

Of particular interest to you would be the article on setting up blocks on a page by default, and the article on using images as navigation items, which shows you how to set and retrieve page attributes, useful for page lists with thumbnail images.

Also relevant is the previous / next add-on, which will allow you to easily paginate between your detail pages.

Good luck!

Basically what you want to do is make a page-list template which will list each item with its description (each item should have its own page), take a look at this link for help:
http://www.codeblog.ch/2009/03/concrete5-templates/2/...

Hope this helps

Matt