You don't mention whether you intend to host the tutorial yourself.  If not, you might consider setting up a blog on wordpress.com where you can use the [sourcecode] tag when composing a post that provides all sorts of options for displaying text from various programming languages.<p>HTML used to be supported, but I don't see it in the current list.  You might just use 'text' as the language type and then use one of the other options to highlight lines and such.<p>You can see a complete description here:<p><a href="http://en.support.wordpress.com/code/posting-source-code/" rel="nofollow">http://en.support.wordpress.com/code/posting-source-code/</a>