Customize the dynamic page title
From Joomla! Documentation
To customize the page title to add the site name followed by the document title, edit index.php in the template that you are currently using. For example, directly after the <head> tag add the following to show "Site Name - Page Name" as the browser's page title:
<?php
$document =& JFactory::getDocument();
$document->setTitle($mainframe->getCfg('sitename') . " - " . $document->title);
?>
