Uploading website files to a domain server makes a website publicly accessible online. The server stores all the necessary files, such as HTML, CSS, and images, and delivers them to a user's browser when they visit the domain name. This process essentially connects the human-friendly domain address to the physical location of the website files, allowing anyone to view the site from anywhere in the world.
Upload files under the document root of the domain hosted in the server. Typically, the path to upload files should be /home/username/publlic_html.