I have copied the whole of the terminal - wasnt sure if i had put previous commands in right
dave@dave-laptop:~$ ls /media
cdrom cdrom0
dave@dave-laptop:~$
dave@dave-laptop:~$ sudo mkdir /media/external-ntfs; sudo mount /dev/sdb /media/external-ntfs; ls /media
[sudo] password for dave:
mount: you must specify the filesystem type
cdrom cdrom0 external-ntfs
dave@dave-laptop:~$ ls /dev/sdb*
/dev/sdb /dev/sdb1
dave@dave-laptop:~$ sudo mount /dev/sdb1 /media/external-ntfs; ls /media
cdrom cdrom0 external-ntfs
dave@dave-laptop:~$