If you want to customize a template ( logo.gif, color, font or background) and don´t know the css class, please use Firefox with the Firebug extension. Now you can analyze every CSS style for customizing the template CSS. Firebug Tutorial
Finding the right CSS file in your theme
As you might already have noticed, next to each css-selector (in our case .toolbar-outer) a filename and a line number are being displayed. Just hover over it and you will see the full path to the file. To learn more about your template's directory structure have a look at this tutorial.
Tip: Disable the theme's Gzip and Compression feature or any other caching script you may be using on your your site when you start out on customizations. If you don't do this, you will not see the file and line locations of the code you want to customize and you also will not see changes you made immediately. Also remember to frequently clear browser caches.
Please never edit the original CSS files, because these files will be overwritten with the next theme update. Always add your custom style to the custom.css
Video, how to customize a Template
How to customize a Joomla theme with using the developer tools from Google Chrome or Firefox. Each modern Browser have a developer tool - Press "F12" - and inspect the "div" and styles.