To upload files to the server, use an FTP / SFTP connection. Such a connection is possible with the use of FTP clients, such as WinSCP, Total Commander, FileZilla, and Cute FTP.
The SSL certificate is used to encrypt the connection between the user, website visitor, and the web server. Thanks to its use, the data exchanged between the website and the server are protected against unauthorized reading, and this is important, in particular, with regard to the protection of passwords, personal data and credit card numbers. The choice of the type of certificate depends on the level of protection that the website owner wants to provide to its users.