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);
?>
