When you have root-level access to a server, it indicates that you'll have full control over it. In other words, you'll be able install any server-side app whatever the changes that it will make to the software environment on your server, and you'll be able to both access and customize any kind of file, which includes system files, and modify various settings. You can do this by connecting to the server as a root user that has full privileges to do the aforementioned things and also to generate other users, including users that also have full privileges. This connection can be established with a web-based graphical interface or a Secure Shell console. For safety reasons, it's recommended that you create one more user for your daily work and use the root user only when you need to modify the server or to set up software that may be required by some script-driven app that you would like to run.