Thank you very much now my new partition is created "/dev/hda4". fdisk gives:
Disk /dev/hda: 81.9 GB, 81964302336 bytes
255 heads, 63 sectors/track, 9964 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/hda1 * 1 13 104391 83 Linux
/dev/hda2 14 6514 52219282+ 83 Linux
/dev/hda3 6515 6628 915705 82 Linux swap
/dev/hda4 6629 9964 26796420 5 Extended
Now, I want to format my hda4 partition. How? Sorry, I look stupid but I don't want to take the change to try something by myself and loose my existing stuff...
Of course, once formatted, I want to mount it at boot time. Again, I would be glad if you could tell me how.
Linux world is pretty hard but fortunately there is a very friendly and resourcefull community!