how to change resolution

["abdelkader belahcene" <abelahcene@gmail.com>]

Hi,
I want to change  screen resolution not only for user (it is done from the menu),  but for every body as root.
There is no mode resolution in last version of xorg.conf ?
in previous there was
modes  with diffrent resolution 800x600, 1024 ......

thanks for help