You can learn to program Java Script. Click here to learn to program Jave Script 2. As your site grows you may want to add a Chat Room , to give user with the same interest of your site to exchange information, or just chat. Click here to select a Chat Room. An even deeper level of web programming is CGI script .
All major sites use CGI script.
CGI scripts allow webpages to move beyond being static and react to user input. Which you don't usually have access to if your site is hosted by someone else. But there are ways around that. You can access CGI script from someone else's root. Click here for free CGI Scripts.