martha505

hello
i use kubuntu 7.10 and i'm a newbie to linux.
few days ago a friend brought a portable hard disk, connected it with my
laptop and it was mounted normally. i could copy her files to my
computer, but when i tried to copy my files to the disk, it wasn't
possible. i tried to change permissons by right-clicking the disk icon
in dolphin and choosing propreties, but i couldn't change them because i
wasn't root.
what should i do?
thanks in advance