You have to add a four celled widget area to get four side by side widget areas. The code below should do that for you. If you read through the stuff in the Add New Widget Areas section some of the info will start to make sense. The code snippet below is just the example with a few changes.
<?php bfa_widget_area('name=Footer widget area&cells=8&before_widget=<div id="%1$s" class="footer-widget %2$s">&after_widget=</div>'); ?>