Generally Shared Seedboxes come with only SSH access (Secure Shell )access , which is like a aterminal acess to your seedbox , to access it the server address is required and the username and password for your seedbox
The software you need for this is called putty , you can download putty from the below link
Once you have installed the application it will look something like this
Once you have this screen put in your own ip address or server address that is provides by your seedbox provider.
which would open up a dos like terminal asking for username
put in your username and then put your password to login , it will give you the SSH access to your seedbox.