Vi is a great editor and it is on pretty much every system, however it can be difficult to learn. It is mode based, so to start typeing hit "i" (minus the quotes) then edit your file. when your done hit esc to get into command mode and hit :x to save and quit, :q! to quit without saving.
The problem with your xorg.conf is you dont have values for your vertical refresh. Find the specs for your monitor (in your manual or online) and enter the correct values.