For list of disks, use sudo fdisk -l or list partitons in GParted (select disk in the top right corner)
When using GParted to resize a disk you might get a message that the volume isn’t clean. To fox this use sudo ntfsfix /dev/<your partition> , for example sudo ntfsfix /dev/sda1
ntfsfix comes from package ntfsprogs and you also need the driver for NTFS, ntfs-3g (NTFS read/write driver for FUSE). Both seem to be installed by default in Ubuntu. If not use sudo apt-get install ntfs-3g and sudo apt-get install ntfsprogs from a terminal windows or use Ubuntu Software Center to install.
