If you want something like a wiki but cleaner I would reccomend using joomla.
By adding the JCE text editor it is easy and quick to add images to articles.
By adding code citation it is easy to add highlighted code in virtually any language, I think over 150 languages are supported.
For additional file uploading I would recommend using JFU Flash Uploader, incredibly easy to use, lightweight and intuitive uploader.
I am setting up an html/css/php learning site for work using this setup myself. I went through a few alternatives before falling back on joomla. Wordpress didnt have any good code highlighting capabileties, Drupal is way too time consuming to set up and maintain, Wikis were too messy. Joomla is very simple to use and set up. It also have print friendly print and PDF versions of all articles
So the procedure would be to get joomla installed, install JCE and Code Citation, both are free. A file uploader, my reccomendation (JFU) cost money, I think 50 euro for unlimited domains and 10 euro for one domain. 80 euro for source I believe. Trial is available and supports uploads of 2mb files. There are alternative file uploaders.
Redmine might be another system to look at, but it is more of a project management system much like trac.
If you want more information on the joomla solution you can contact me on MSN.