add span to blog title?

What you have (in your posting) looks alright but the code that I see in your live blog is:

<a href="http://ordinaryimages.com/" title="Home">ordinaryimages</a><br /><span id="span"></span></div>

Which doesn’t look OK at all.
Should be:

<a href="<?php bloginfo('url')" title="Home"><span style="color: #ccc;">ordinary</span><span style="color: #ffa800;">images</span></a>

Font size can also be set in <span> tags. But you should really be setting your styles in you style.css file. The following *should* work for you:

style.css

.grey{color:#ffa800;font-size:1em;}
.orange{color:#ccc;font-size:1.5em;}

header.php
<a href="<?php bloginfo('url')" title="Home"><span class="grey">ordinary</span><span class="orange">images</span></a>

NOTE: you will probably want to adjust the font sizes.

It might be mentioned that you have 19 errors in you html alone. Please validate your code.