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.
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.