Please write small capitals.
(you did switch off your machine and reboot back into desktop ? )
In "system tools" there is entry "system settings" - there again you can adjust
behaviour of your desktop-environment.
In "brightness and lock" you can change the time from 10 minutes up to one hour. I would set it on 30 minutes.
Then you have enough time to open konsole resp. terminal for to set a password. - better you have at least one password, than no password.
In Terminal is command:
then you enter your password twice.
now it is better to have a second password as admin of your netbook.
(you type your new password from just before)
then you enter again your second password twice (different password).
now your system is double-safe !
two times command
and you are normal User again for your machine.