How do I increase space in "/" directory?

To help you in a good way we need some additional info about your hard disk partitions...

So please open a terminal and copy and paste here the result of this command:

sudo fdisk -l

the system will ask you a password please type your user password, you don't receive any chars feedback when you type your password in the terminal so please type it then press enter.

Thank you

Still waiting detailed informations about your system you can resize your hard disk partitions by using the Ubuntu standard desktop install cd.
I mean you must boot your pc entirely from Ubuntu Live install desktop cd and you can use gparted, call it from the menu: System → Administration → Partition Editor

Hope this helps

How about this? how many o/s there, is that enough for ubuntu space
benny@b3nY:~$ sudo fdisk -l
[sudo] password for benny:
Sorry, try again.
[sudo] password for benny:

Disk /dev/hdc: 80.0 GB, 80026361856 bytes
255 heads, 63 sectors/track, 9729 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x16ed16ed

   Device Boot Start End Blocks Id System
/dev/hdc1 * 1 5287 42467796 7 HPFS/NTFS
/dev/hdc2 5288 9541 34170255 83 Linux
/dev/hdc3 9542 9729 1510110 5 Extended
/dev/hdc5 9542 9729 1510078+ 82 Linux swap / Solaris

Disk /dev/sda: 160.0 GB, 160041885696 bytes
255 heads, 63 sectors/track, 19457 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x00d700d7

   Device Boot Start End Blocks Id System
/dev/sda1 * 1 6048 48580528+ 7 HPFS/NTFS
/dev/sda2 6049 19456 107699760 f W95 Ext'd (LBA)
/dev/sda5 6375 19456 105081133+ 7 HPFS/NTFS
/dev/sda6 6049 6352 2441817 83 Linux
/dev/sda7 6353 6374 176683+ 82 Linux swap / Solaris

Partition table entries are not in disk order

this one is different before someone rush the answer
benny@u804:~$ sudo fdisk -l

Disk /dev/sda: 160.0 GB, 160041885696 bytes
255 heads, 63 sectors/track, 19457 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x00d700d7

   Device Boot Start End Blocks Id System
/dev/sda1 * 1 6048 48580528+ 7 HPFS/NTFS
/dev/sda2 6049 19456 107699760 f W95 Ext'd (LBA)
/dev/sda5 6375 19456 105081133+ 7 HPFS/NTFS
/dev/sda6 6049 6352 2441817 83 Linux
/dev/sda7 6353 6374 176683+ 82 Linux swap / Solaris

Partition table entries are not in disk order

Disk /dev/sdb: 80.0 GB, 80026361856 bytes
255 heads, 63 sectors/track, 9729 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x16ed16ed

   Device Boot Start End Blocks Id System
/dev/sdb1 * 1 5287 42467796 7 HPFS/NTFS
/dev/sdb2 5288 9541 34170255 83 Linux
/dev/sdb3 9542 9729 1510110 5 Extended
/dev/sdb5 9542 9729 1510078+ 82 Linux swap / Solaris

I'm just to try read in one page but just minute restore using apt-get install ubuntu-desktop fail

Boot you computer with a liveCD , and open system-->administration-->gparted partition editor. You'll see a graphic representation of your hard drive(s), and you'll be able to resize partitions so that the one where you neer more space actually gets it.
Hope you find this useful