The X Window System comes by default with an english keymap on most distributions. If you have a
keyboard from another country, it may be a problem.
The XKB extension was provided for that purpose. If you look in your X configuration file, usualy in
/etc/X11 called XF86Config or xorg.conf, you will find a section about the keyboard. There, you may specify several
parameters, including the keymap and keycodes to use.
For a list of available keymaps, you can look in your X directory. Most of those keymaps are also available
from the graphical configuration program, XF86Setup or xorgsetup .