First off you need an FTP client application. We recomend File Zilla which is a free download from here - https://filezilla-project.org/download.php
Next you need to create a 'site' by clicking on the file menu, then choosing site manager.
For the host field enter your domain name or your server ip address if you know it.
Port can be left empty, it should use port 21 the ftp standard.
Protocol is FTP not SSH.
Logon type is Normal.
Enter the user id and password you were given when you signed up or recreate new credentials from the 'content' menu of your dashboard.
Almost done.
Be sure to change the 'encryption' from 'use plain ftp' to 'Require Explicit FTP over TLS'.
If you still cannot connect create a support ticket.
While this is a buit of a nuisance, you would not want a Chinese hacker uploading pictures of cats to your webstore while you are asleep... Not kidding (has happened before).
