You will have to install a server uploading program in your computer, like Filezilla client, which is free.
As soon as you do, use the passwords/codes we will have sent you by email to connect to the server and installl all your files in the httpdocs folder.
There is also another way through your Plesk or Cpanel control panel. Open the Filemanager folder and install all your files in the httpdocs folder.