This goes in your HTML where you want the menu, or other file, to appear:
<script language="JavaScript" type="text/javascript" src="js/menu.js"></script>
Create a new file called "menu.js"
document.write('<ul class="menu">');
// START LINKS //
<!-- Copy and paste to add more links. Note the first link starts the list, so don't copy that. -->
document.write('<li>');
document.write('<a href="index.html" class="menu">Home</a>');
document.write('</li><li>');
document.write('<a href="about.html" class="menu">About Us</a>');
document.write('</li><li>');
document.write('<a href="services.html" class="menu">Services</a>');
document.write('</li><li>');
document.write('<a href="gallery.html" class="menu">Photo Gallery</a>');
document.write('</li><li>');
document.write('<a href="testimonials.html" class="menu">Testimonials</a>');
document.write('</li><li>');
document.write('<a href="contact.html" class="menu">Contact Us</a>');
document.write('</li>');
// END LINKS //
document.write('</ul>');