Most of the present Ubuntu Operating Systems will auto-mount the internal/external disks.
In some cases that may not be done automatically. In that situation, you can manually mount the media to the Ubuntu.
Here comes the mounting of external disks like HDD, Pen-drive etc in Ubuntu.
1) Open terminal
2) Type sudo su in the terminal
3) Enter the password
4) Now you will be in super user mode i.e. # mode
5) Go to the desktop or some folder where you want to create a folder for mounting
ex: # cd /home/user1/Desktop
6) Create a directory
ex: # mkdir ExtrnDisk
7) Type the following command for NTFS disks
# mount -t ntfs-3g /dev/sdb1 ExtrnDisk/ (FAT32 -- vfat)
Type the following for rest of the disks
# mount /dev/sdb ExtrnDisk/
8) Now you can see the drive contents mounted to ExtrnDisk folder