Gets off his bicycle and tries to help some more...
You cannot style content that is not output, that is available to be rendered with CSS.
Here is the current HTML:
<nav id="site-footer-navigation">
<div class="menu-footer-navigation-container"><ul class="nav-menu footer-menu" id="menu-footer-navigation"><li class="menu-item menu-item-type-post_type menu-item-object-page menu-item-816" id="menu-item-816"><a href="http://pbycatalina.com/project-acknowledgments/">Credits</a></li>
<li class="menu-item menu-item-type-post_type menu-item-object-page menu-item-817" id="menu-item-817"><a href="http://pbycatalina.com/tcps-copyright-permissions/">Copyright</a></li>
<li class="menu-item menu-item-type-post_type menu-item-object-page menu-item-818" id="menu-item-818"><a href="http://pbycatalina.com/contact-us/">Contact</a></li>
<li class="menu-item menu-item-type-post_type menu-item-object-page menu-item-3910" id="menu-item-3910"><a href="http://pbycatalina.com/tcps-faq/">FAQ</a></li>
<li class="menu-item menu-item-type-post_type menu-item-object-page menu-item-3312" id="menu-item-3312"><a href="http://pbycatalina.com/login/">Log In</a></li>
</ul></div> </nav>
So all 5 items are being output in HTML (review how we post here, it is often to also help others with similar issues, so we may include clarifications).
Now, this is what is currently is CSS:
#menu-footer-navigation li.menu-item-816 a{background:url('img/BRNSTRMRCBR1.jpg') no-repeat top center;}
#menu-footer-navigation li.menu-item-817 a{background:url('img/cansoblister4.jpg') no-repeat top center;}
#menu-footer-navigation li.menu-item-818 a{background:url('img/LancasterRadio1.jpg') no-repeat top center;}
#menu-footer-navigation li.menu-item-3910 a{background:url('img/prop.jpg') no-repeat top center;}
#menu-footer-navigation li.menu-item-3921 a{background:url('img/prop.jpg') no-repeat top center;}
Please compare to above.