Please don't put a Serv-U 4.1.03 server on the Internet. That software is nearly ten years old and contains several security flaws that have since been uncovered. (I should know - I work for RhinoSoft
, the author of Serv-U.)
These days Serv-U FTP Server (v.11+) is used primarily by businesses to securely exchange files with partners, to provide employees and contractors remote access to their files or, As Orbital Shark noted, to host web sites. Access to the server is made via web browsers, via mobile devices or via traditional FTP, SFTP or FTPS and user interfaces have progressed to the point where end users almost never need to install any client software on their desktops to work with their data.
If you're just curious what a file transfer server can do, please take a look at a modern version of Serv-U - it even includes wizards to set up the things you need to step through manually here - and skip this tutorial.