I can't find my xorg.conf.
There is no xorg.conf file by default in Ubuntu 11.04.
If I run: "whereis xorg.conf" I am seeing: xorg: /usr/lib/xorg /usr/lib64/xorg /usr/include/xorg
may be I just can create it by myself? at /etc/X11/xorg.conf?
To create an initial /etc/xorg.conf file, you can have Xorg's autoconfiguration output a full blown static one for you:
sudo Xorg -configure
or create an /etc/xorg.conf containing only those sections and options that you need to override Xorg's autoconfigurated settings.
The modern implementations of Xorg doesn't need a xorg.conf file, the configuration is automatic. And the correct place for the xorg.conf file is /etc/X11/xorg.conf.