When you have root-level access to a server, it means that you will have full control of it. In other words, you can set up any server-side application no matter what the changes that it will make to the software environment on your server, and you're able to both access and customize any kind of file, which includes 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 make other users, which includes users that also have full privileges. This connection can be established using a web-based graphical interface or a Secure Shell console. For safety reasons, it's recommended that you make a separate user for your everyday work and use the root user only when you need to modify the server or to set up software that may be needed by some script-driven app that you wish to run.