To change your server's hostname:

1. Login to your client's area from yourserver.se
2. Select Services — My Services
3. Go to"View Details" next to the server, you want to change the hostname for
4. Click "Change" button next to the existing hostname of your server.

Changes will be made immediately both in your client's area and inside your server.
Please note, that server's hostname is set every time it starts, so changing hostname inside your server (i.e. in /etc/hostname or /etc/sysconfig/network) is not preserved after reboot.