Remember that the code needs to be after the opening <body> tag and before the </body> tag.
<body>
<!--All code below the opening BODY will be visible-->
<div id="frame">
<header>
<div id="header_logo">
<!--Closing Tag for header_logo--></div>
<nav>
<!--This code references the menu icon that is visible for mobile views only-->
<a href="#" id="menu-icon"></a>
<!--The Navigation is created using an Unordered List-->
<ul>
<!--This is where the Navigation Button #1 goes.-->
<li> <a href="gallery_1.html" title="Gallery Page #1" target="_self">Page Name #1 Link</a></li>
<!--This is where the Navigation Button #2 goes.-->
<li> <a href="gallery_2.html" title="Gallery Page #2" target="_self">Page Name #2 Link</a></li>
<!--This is where the Navigation Button #3 goes.-->
<li> <a href="gallery_3.html" title="Gallery Page #3" target="_self">Page Name #3 Link</a></li>
</ul>
</nav>
<!--Closing Tag for header--></header>
<div id="intro">
<!--Closing Tag for intro--></div>
<div id="stage">
<div id="col_1">
<!--Closing Tag for col_1--></div>
<div id="col_2">
<!--Closing Tag for col_2--></div>
<div id="col_3">
<!--Closing Tag for col_3--></div>
<!--Closing Tag for stage--></div>
<div id="footer">
<!--Closing Tag for footer--></div>
<!--Closing Tag for Frame--></div>
</body>