To download file you can use php script as it is described here, but in Joomla! you must add this line of code:
ĂÂ while( @ob_end_clean() );
Taken from here.
You should switch to html view and enter, for example:
<pre xml:html><!-- your HTML code here --></pre>
Don't forget to turn on GeSHi plugin in the plugin manager!
Taken from here.ĂÂ
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