Using of the Dottoro Highlighter plugin is really simple. Just insert your code snippet in the Visual or HTML view, select it and press the Dr-Highlight button on the toolbar. You don't need to embed your source code into an element (such as PRE), just select the whole source that you want to highlight and press the Dr-Highlight button. Clicking on the Dr-Highlight button pops up a dialog box where you can specify the settings for the highlighted code. If you need to modify the appearance of a previously highlighted code, click into it then click on the Dr-Highlight button on the toolbar.
The default settings for the Dottoro Highlighter plugin can be set on the preferences page. For further description, please visit the Dottoro Syntax Highlighter site.