Yoast Breadcrumbs adds navigation breadcrumbs (covered in Chapter 4 of this minibook) to your site. Although you can install and activate the plugin like any other plugin, you need to go through a few extra steps to get the breadcrumbs to show up on your page. For most standard WordPress themes you need to add the following code into the template where you want the plugin to appear (see Book VI if you need assistance with editing template files):
<?php if ( function_exists('yoast_breadcrumb') ) { yoast_breadcrumb('<p id="breadcrumbs">','</p>'), } ?>