Unlike some years back when web sites were almost exclusively static, the standard nowadays is to have a feature-rich, dynamic site. Few people can create this kind of web site from scratch though, hence the most convenient solution to have a dynamic site is to use a script application. Lots of web hosting companies offer script installers which you can use to add this kind of an app for each of your domain or subdomains, so you will not need to install anything manually. The main benefit of using an installer tool would be that the scripts are ready to use in just a couple of minutes and the copy that will be installed is already with the settings needed for it to run properly on the specific hosting web server, so you'll not need to alter any script or account settings. That way you can easily create one with only a few clicks even when you have never had a site before.