Open a terminal and log in as root. After each thing i say ill tell you the command.
root
(will ask for password, enter it)
Now you will enter a command that will display your current partitions.
df -h
df doesnt stand for anything, just a command, but the -h means human-readable.
Notice the partitions are HDA1, HDB1, ect. HD means harddrive if they're SATA drives it will be SDA, A is just like a number so its HD number 1. And 1 is the partition number.(Some people are clueless to this....) So you will pick the drive you are adding out of the results out of that command.
Now you need to mount the partition. For the linux newbie a mount is simply a shortcut. First we need to make the dir for it. So...
mkdir /dev/hda1
HDA1 is an example of course.
Now we have to add a line to the fstab file.
gedit /etc/fstab
You will get results similar to this:
LABEL=/ / ext3 defaults 1 1
LABEL=/boot /boot ext3 defaults 1 2
none /dev/pts devpts gid=5,mode=620 0 0
LABEL=/export /export ext3 defaults 1 2
none /proc proc defaults 0 0
none /dev/shm tmpfs defaults 0 0
/dev/hdb2 swap swap defaults 0 0
/dev/cdrom /mnt/cdrom udf,iso9660 noauto,owner,kudzu,ro 0 0
/dev/fd0 /mnt/floppy auto noauto,owner,kudzu 0 0
Now you will simply add the line relevant to what your partition is. So say:
/dev/hda2 /newpartition vfat defaults 1 2
Whatever you put as what i put newpartition will appear mounted in / which is what you see when you double click filesystem. VFAT is linux for FAT32. The digits "1 2" refer to whether the mount point should be backed up when the dump command is used and disk integrity checks using fsck. The "1" states that it should be backed up when the dump command is issued (0=no). The "2" refers to the order in which "fsck" should check the mount points. The digit "1" identifies the root ("/") of the filesystem. All others should be "2". (0=no check)
After that, one more command.
mount /dev/hda1
Reboot and your partition is mounted.
I had to look up a few things that i couldn't remember haha. Been awhile since i've been on Linux.