• The choice of which application to download depends first on your level of html/css/php/mysql knowledge, for two reasons : first one to adapt your site to your layout requirements, and second some applications are quite complex and require some development before they can be fully exploited.
• The thing is, all applications we'll recommend  come with a self installing  browser based wizard. In all cases the only thing you'll need to know is your PHP and Mysql version and connection details (host, user, password, database name), usually your host does no secret about that. A good thing to check out too is the phpinfo page that tells you everything about php configuration,  installed modules and apache server details. For instance most modern Content Management Applications require a graphic libray to be installed : that can be either gd, netbpm or image magick...
• Of course, all beginners stuff also applies to experienced developpers.

For beginners we recommand various applications depending on the type of web site you want :

• if you want a simple looking web site with categories and a comment system, why not go for a blog ? Wordpress is a great blog with lots of possibilities, and thousands of predefined layouts are available if you care to use the online template editor 
• If you're looking for a more complex application with portal functions like forum, links and download management, then we strongly recommend to try out mambo. It has  great looking interface and is used by thousands of enthusiasts all around the world. That means it's not going to stay put and is going to evolve constantly. you can try the administration interface with user admin and password admin at the mambo demosite.

For users with a limited knowledge of web site development technologies, I'd recommand to have a look at phpwcms. This content management solution is developped by one guy only but is quite versatile and allows some level of customization with very little browser based administration tasks. The only thing is that there are no predefined template archive and you'll have to design yours from the default template.

For advanced developers, here is a list of applications we could recommand :

• Ezpublish is a framework that can deal with all sort of datatypes : in fact it's the administrator who defines the datatype to be dealt with  : content, link, image, what ever your database schema is, ezpublish can do with it.
• typo3 offers the same kind of flexibility but again with that one the learning curve is steep, don't expect to get your site up and running in an hour.