Once you get beyond a few hand-coded HTML pages on a site, you're probably looking at getting into server-side coding and probably a database with it. If you follow a Model/View/Controller (MVC) pattern, the controller will respond to different URLs to determine what server-side processing needs to be done, then output the results using applicable views and associated resources (JavaScript and CSS files, for example). If that's a whole lot of meaningless words to you -- or you just want to be more efficient with your time -- you might just want to search for an existing Content Management System (CMS) that would pretty much do what you need out of the box. (Could be something like WordPress, or something more general like Joomla, plus many other things that might be out there for niche purposes.)