Tired to search for normal, easy to install programming code highlight plugin?
This one will help you to end this adventure.
It adds special shortcode [code][/code], keyboard shortcut «alt+c» and button to Visual Editor.
If you want do define highlight syntax language, you may use direct lang param like [code php][/code].
Plugin will also highlight <pre class='language-html'>…</pre> and <code class='language-html'></code>, if you don’t want to use shortcode.
This plugin is available for download for your site.