How to make an xorg.conf file

I just installed Ubuntu 12.10 and I need to make a custom xorg.conf file. By default, there is not an xorg.conf file on my system. I know what I need to write in the config, but I just don't know how to make X load it...

Should I put my custom commands in a file that already exists? Where is it? Should I make my own xorg.conf file and put it in /etc/X11?

If you would want full and proper xorg.conf file (tested on Ubuntu 12.10):

1. Switch to console mode: Ctrl+Alt+F1

2. Kill x server:

   sudo service lightdm stop
   

3. Generate new xorg.conf file:

   sudo X -configure
   

   This will create xorg.conf.new file in your current directory.

4. Rename and move:

   sudo mv xorg.conf.new /etc/X11/xorg.conf
   

5. Return to GUI:

   sudo start lightdm
   

taken from Linux Mint forums (go to point 3. In Mint, xorg.conf is not present by default...)

For Nvidia based cards I suggest to install the binary driver from the repositories and then run nvidia-xconfig. It will create a fishbone with basic configuration. Similar commands for other binary drivers may exist.

If there isn't, just start by creating the file and enter your settings.

All configuration not set will X find by itself. It has a lot of heuristic, but yes, it may be hard to find the right setting keywords and values in order to tweak everything to your needs.

Figured it out. It's as simple as making a file called "xorg.conf" and putting it in "/etc/X11/". I guess I thought that seemed too simple :P

X will read the config file and try to accept your statements. It will then auto config anything you don't explicitly say.