It's ok.
There's many many many many many many many many command line editors.
But, if you want to just get the job done. "pico" is a good newbie choice.
root@shell: $ pico /etc/X11/XF86Config
(a neat little trick, type 'pico /etc/X' then hit the TAB key and it will auto complete for you
Just in case you didn't already know that)
Then you will do as I instructed in the above post.
You can do searches in pico by hitting "ctrl+w" and then putting in a search string. To do multiple searches just hit "ctrl+w" again and it will search for the next instance.
Once you find what I instructed above add that line.
Then once you have done that hit "ctrl+x" then hit "y" and then enter. It's now saved and you should be able to use your scroll.