This is tricky to help you with since there is very little info here...
which distro are you using?
(your distro and location should be in your profile)
kernel version?
what do you mean "nothin happens"? You typed in the command and then ... the prompt came back right away? The curser just sat there until you hit ctrl c?
What have you done to check this out? Have you tried checking what you have done against:
http://www.xfree86.org/4.5.0/Install.html
It sounds like the autoconfig isn't detecting your videocards and so on. Have you tried "XFree86 - configure"?
Or, it could be that the config has been successful - and you need only reboot. So long as you are set to boot into runlevel 5, the server should start fine.
You can check the configuration - it is usually /etc/X11/XFree86.conf or something.
Lastly, you should realise that most major distros do not use XFree86 server because of changes they made to their licence. You should consider converting your server to Xorg.
