Glad you figured it out. If you are new to Wordpress it can take a while to understand how things work. A Devin said, the dummy content is very useful to see how all the different elements work in the Shoutbox theme.
If you are going to start changing your css I would recommend changing the custom.css file which is inside the wp-content/themes/shoutbox/css/ folder of your online archives. Make a copy of it to your desktop, make the changes and then upload the new file to that same address in your online site, replacing the file that is already there.
A great way to learn how css work is to use Firebug, which is an add on you can get for Firefox. You use the select option to highlight the piece of the page you want to examine/change and Firebug displays the css code for you. You can even change the code inside firebug and play around with the page you are viewing to see what effect the changes make, before copying and saving the changes to your custom.css file.
Other browsers probably have tools for examining web pages too.
You should also make regular backups of your site files (the files and the database) as you go along in case something crashes along the way. The database is stored in a different place. You need to access phpmyadmin in your server control panel to get to it. There are some useful plugins for WP that can help with backups to save you doing it manually, but its good to know how to do it the long way, just in case.
Good luck. We were all new at this once - don't worry!