You have add bredcum by two ways:
1. Via code (Add in a controller):
$crumbs = Mage::app()->getLayout->getBlock('breadcrumbs');
$crumbs->addCrumb('home', array(
'label' => 'Home',
'title' => 'Go to Home Page',
'link' => Mage::getUrl('')
));
2. Via Layout XML:
<reference name="breadcrumbs">
<action method="addCrumb">
<crumbname>home</crumbname> <!-- Class Name Which apply on li -->
<crumbinfo>
<label>Home</label>
<title>Go to Home Page</title>
<link>/</link>
</crumbinfo>
</action>
<action method="addCrumb">
<crumbName>cb</crumbName> <!-- Class Name Which apply on li -->
<crumbInfo>
<label>CB</label>
<title>CB</title>
</crumbInfo>
</action>
</reference>