If you have root-level access to a server, it indicates that you'll have full control over it. In other words, you can install any server-side app no matter what the changes that it'll make to the software setting on your server, and you are able to both access and change any file, including system files, and modify any settings. You can do this by connecting to the server as a root user that has full privileges to perform all these things and to create other users, which includes users that also have full privileges. This connection can be established with a web-based graphical interface or a Secure Shell console. For security reasons, it's recommended that you make another user for your everyday work and use the root user only when you need to modify the server or to install software that may be required by a script-driven application that you would like to run.