When you have root-level access to a server, this means that you'll have full control over it. That is to say, you'll be able set up any server-side app no matter what the changes that it'll make to the software environment on your server, and you'll be able to both access and modify any kind of file, which includes system files, and change various settings. You can do this by connecting to the server as a root user that has full privileges to do all these things and to make other users, which includes users that also have full privileges. This particular can be established using a web-based graphical interface or a Secure Shell console. For security reasons, it is recommended that you create another user for your everyday work and employ the root user only when you need to customize the server or to set up software which may be needed by some script-driven app that you wish to run.