Just a tip but you can best work with CSS in your head or the very best way is to use an external CSS file. Also when you use the img attribute you need to give it an "alt" attribute otherwise the validator will give errors. And the are some other faults in it. The best validator there is, is this one
http://validator.w3.org
EDIT: rewrote the entire code so it has no errors anymore (still has a lot but that because the website's don't exist and are whit space).
<!DOCTYPE html>
<html>
<head>
<title>DarkBASIC Professional Help File</title>
<meta charset="UTF-8">
<style type="text/css">
body {
background: url("gfx/dbpro_bg.jpg");
font-family: Verdana;
}
header, img{
border: 0px;
}
footer {
text-align: center;
margin: 0px auto;
}
.navbar {
border-collapse: collapse;
margin: 0px auto;
}
navbar, td {
padding: 0px;
}
#index {
text-align: center;
}
h1 {
font-size: 32px;
margin: 0px;
}
#alphabet > li {
display: inline;
font-size: 18px;
font-weight: bold;
}
#line {
vertical-align: top;
}
#list {
list-style-type: none;
padding: 0px;
font-size: 18px;
font-weight: bold;
}
.list2 {
list-style-type: none;
padding: 0px;
font-size: 14px;
font-weight: normal;
}
</style>
</head>
<body>
<!-- Page Header -->
<header>
<table class="navbar">
<tr>
<td><img src="gfx/dbph_head_1.jpg" alt="logo" width="102" height="51" /></td>
<td><a href="main.htm"><img src="gfx/dbph_head_2.jpg" alt="main" width="47" height="51" /></a></td>
<td><a href="commands.htm"><img src="gfx/dbph_head_3.jpg" alt="commands" width="50" height="51" /></a></td>
<td><a href="examples.htm"><img src="gfx/dbph_head_4.jpg" alt="examples" width="47" height="51" /></a></td>
<td><a href="documents.htm"><img src="gfx/dbph_head_5.jpg" alt="documents" width="46" height="51" /></a></td>
<td><a href="index.htm"><img src="gfx/dbph_head_6.jpg" alt="index" width="56" height="51" /></a></td>
</tr>
</table>
</header>
<section id="index">
<h1><strong>PLUGIN INDEX</strong></h1>
<img src="gfx/divide.jpg" width="340" height="5" alt="" id="line" /><br /><br />
<nav>
<ul id="alphabet">
<li><a href="#A">A</a></li>
<li><a href="#B">B</a></li>
<li><a href="#C">C</a></li>
<li><a href="#D">D</a></li>
<li><a href="#E">E</a></li>
<li><a href="#F">F</a></li>
<li><a href="#G">G</a></li>
<li><a href="#H">H</a></li>
<li><a href="#I">I</a></li>
<li><a href="#J">J</a></li>
<li><a href="#K">K</a></li>
<li><a href="#L">L</a></li>
<li><a href="#M">M</a></li>
<li><a href="#N">N</a></li>
<li><a href="#O">O</a></li>
<li><a href="#P">P</a></li>
<li><a href="#Q">Q</a></li>
<li><a href="#R">R</a></li>
<li><a href="#S">S</a></li>
<li><a href="#T">T</a></li>
<li><a href="#U">U</a></li>
<li><a href="#V">V</a></li>
<li><a href="#W">W</a></li>
<li><a href="#X">X</a></li>
<li><a href="#Y">Y</a></li>
<li><a href="#Z">Z</a></li>
</ul>
</nav>
</section>
<br />
<nav>
<ul id="list">
<li id="A">A<br /><br />
<ul class="list2">
<li><a href="AVI_PLugin.htm">AVI Plugin</a></li>
<li><a href="Add_Font_Plugin.htm">Add Font Plugin</a></li>
<li><a href="AI_A_star_Pathfinding_Plugin.htm">AI A* Pathfinding Plugin</a></li>
<li><a href="Advanced_Sprites.htm">Advanced Sprites</a></li>
<li><a href="Anisotropic-Filtering_DLL.htm">Anisotropic Filtering DLL</a></li>
<li><a href="Advanced2D.htm">Advanced2D</a></li>
</ul>
<br />
</li>
<li id="B">B<br /><br />
<ul class="list2">
<li><a href="BMP_Font_Plugin.htm">BMP Font Plugin</a></li>
<li><a href="BMP_Font_Kit.htm">BMP Font Kit</a></li>
<li><a href="Blitz_Terrain.htm">Blitz Terrain (Free Version)</a></li>
<li><a href="BBB_GUI_Plugin.htm">BBB GUI Plugin</a></li>
</ul>
<br />
</li>
<li id="C">C<br /><br />
<ul class="list2">
<li><a href="Cartography_shop_importer_plugin.htm">Cartography shop importer plugin</a></li>
<li><a href="Console Plugin.htm">Console Plugin</a></li>
<li><a href="Community commands DLL.htm">Community commands DLL</a></li>
</ul>
<br />
</li>
<li id="D">D<br /><br />
<ul class="list2">
<li><a href="Direct 3D Functions DLL.htm">Direct 3D Functions DLL</a></li>
<li><a href="DKShop & DKAVM Plugins.htm">DKShop & DKAVM Plugins (updated)</a></li>
<li><a href="DarkTCP.htm">DarkTCP</a></li>
<li><a href="Decompression Plugin.htm">Decompression Plugin</a></li>
<li><a href="DB Functions.htm">DB Functions DLL</a></li>
<li><a href="DBConn.htm">DBConn</a></li>
<li><a href="DarkAL.htm">DarkAL</a></li>
</ul>
<br />
</li>
<li id="E">E<br /><br />
<ul class="list2">
<li><a href="Enhanced Audio Plugin V1.51.htm">Enhanced Audio Plugin V1.51</a></li>
<li><a href="Enhanced Audio Plugin V1.55(beta).htm">Enhanced Audio Plugin V1.55(beta)</a></li>
<li><a href="EZ Rotate (Free Version).htm">EZ Rotate (Free Version)</a></li>
<li><a href="EZ Serv Plguin.htm">EZ Serv Plguin</a></li>
<li><a href="Extended DLL Plugin.htm">Extended DLL Plugin</a></li>
</ul>
<br />
</li>
<li id="F">F<br /><br />
<ul class="list2">
<li><a href="Faster File Plugin.htm">Faster File Plugin</a></li>
<li><a href="FTP Plugin.htm">FTP Plugin</a></li>
</ul>
<br />
</li>
<li id="G">G<br /><br />
<ul class="list2">
<li><a href="Goga's Free FTP Plugin.htm">Goga's Free FTP Plugin</a></li>
<li><a href="Goga's SMTP Plugin.htm">Goga's SMTP Plugin</a></li>
<li><a href="Goga's Free DBP Plugin V2.0.htm">Goga's Free DBP Plugin V2.0</a></li>
<li><a href="Grass System Plguin.htm">Grass System Plguin</a></li>
<li><a href="GUI (Windows) Plugin.htm">GUI (Windows) Plugin</a></li>
<li><a href="GameCrypt Plugin.htm">GameCrypt Plugin</a></li>
</ul>
<br />
</li>
<li id="H">H<br /><br />
<br />
</li>
<li id="I">I<br /><br />
<ul class="list2">
<li><a href="Image Kit V2.htm">Image Kit V2</a></li>
</ul>
<br />
</li>
<li id="J">J<br /><br />
<br />
</li>
<li id="K">K<br /><br />
<br />
</li>
<li id="L">L<br /><br />
<ul class="list2">
<li><a href="Live-Update Plugin.htm">Live-Update Plugin</a></li>
<li><a href="Lua 5.1 Plugin.htm">Lua 5.1 Plugin by Barnski.</a></li>
<li><a href="Lua 5.1 Plugin.htm">Lua 5.1 Plugin by Coolgames.</a></li>
<li><a href="Logarithm Plugin.htm">Logarithm Plugin</a></li>
<li><a href="Limb Alpha Plugin.htm">Limb Alpha Plugin</a></li>
<li><a href="Levenshtein String Distance.htm">Levenshtein String Distance</a></li>
</ul>
<br />
</li>
<li id="M">M<br /><br />
<ul class="list2">
<li><a href="Matrix1Util Plugin Collection.htm">Matrix1Util Plugin Collection</a></li>
<li><a href="Multisync Plugin.htm">Multisync Plugin</a></li>
<li><a href="MS Access Database Plugin.htm">MS Access Database Plugin</a></li>
<li><a href="Mappy Plugin.htm">Mappy Plugin</a></li>
<li><a href="Message Box Plugin.htm">Message Box Plugin</a></li>
<li><a href="MultiSync Plugin V1.0 (New).htm">MultiSync Plugin V1.0 (New)</a></li>
<li><a href="MIDI Plugin.htm">MIDI Plugin</a></li>
<li><a href="MP3 Plugin.htm">MP3 Plugin</a></li>
<li><a href="Mathematical Expression Plugin.htm">Mathematical Expression Plugin</a></li>
</ul>
<br />
</li>
<li id="N">N<br /><br />
<ul class="list2">
<li><a href="Newton game Dynamics Wrapper V1.53.htm">Newton game Dynamics Wrapper V1.53</a></li>
<li><a href="nOBC.htm">nOBC</a></li>
</ul>
<br />
</li>
<li id="O">O<br /><br />
<ul class="list2">
<li><a href="Object LOD plugin.htm">Object LOD plugin</a></li>
</ul>
<br />
</li>
<li><a id="P">P</a><br /><br />
<ul class="list2">
<li><a href="Printer Plugin.htm">Printer Plugin</a></li>
</ul>
<br />
</li>
<li><a id="Q">Q</a><br /><br />
<ul class="list2">
<li><a href="QuadTree Plugin.htm">QuadTree Plugin</a></li>
</ul>
<br />
</li>
<li><a id="R">R</a><br /><br />
<ul class="list2">
<li><a href="RTS Build Order DLL.htm">RTS Build Order DLL</a></li>
<li><a href="RAR Plugin.htm">RAR Plugin</a></li>
</ul>
<br />
</li>
<li><a id="S">S</a><br /><br />
<ul class="list2">
<li><a href="SR Plugin.htm">SR Plugin</a></li>
<li><a href="Sparky's Collison DLL V2.0.htm">Sparky's Collison DLL V2.0</a></li>
<li><a href="SIRDs.htm">SIRDs</a></li>
<li><a href="SC68 Player Plugin.htm">SC68 Player Plugin</a></li>
<li><a href="Screen Capture DLL.htm">Screen Capture DLL</a></li>
</ul>
<br />
</li>
<li><a id="T">T</a><br /><br />
<ul class="list2">
<li><a href="Tempest.htm">Tempest</a></li>
<li><a href="Timing Plugin.htm">Timing Plugin</a></li>
<li><a href="Timer Based Movement.htm">Timer Based Movement</a></li>
</ul>
<br />
</li>
<li id="U">U<br /><br />
<ul class="list2">
<li><a href="Utility Functions Collection.htm">Utility Functions Collection</a></li>
</ul>
<br />
</li>
<li id="V">V<br /><br />
<br />
</li>
<li id="W">W<br /><br />
<ul class="list2">
<li><a href="Winsock 2.2 Plugin.htm">Winsock 2.2 Plugin</a></li>
<li><a href="Window Skinning Plugin.htm">Window Skinning Plugin</a></li>
</ul>
<br />
</li>
<li id="X">X<br /><br />
<ul class="list2">
<li><a href="XML Plugin.htm">XML Plugin</a></li>
<li><a href="Xbox 360 Controller Plugin.htm">Xbox 360 Controller Plugin by Raven.</a></li>
<li><a href="Xbox 360 Controller Library (full).htm">Xbox 360 Controller Library (full) by Todd Riggins.</a></li>
</ul>
<br />
</li>
<li id="Y">Y<br /><br />
<br />
</li>
<li id="Z">Z<br /><br />
<ul class="list2">
<li><a href="ZLib Plugin.htm">ZLib Plugin</a></li>
</ul>
</li>
</ul>
</nav>
<br />
<!-- Page Footer -->
<footer>
<img src="gfx/dbph_foot_1.jpg" width="340" height="38" alt="footer"></td>
</footer>
</body>
</html>
If you need help, I can help after Thursday, I got exam of webdesign then.