There are lots (and I mean LOTS) of links floating around in this forum about creating a child theme.
Definitely check out the resources here:
https://forum.graphene-theme.com/graphene-support/beginners-resources-possible-sticky
This page will show you how to target your CSS to just one particular page or post:
http://blog.kjodle.net/2012/02/24/styling-wordpress-posts-pages-archives-and-home-pages-by-class/
Biggest/best hint of all: use Firebug.
Your code will look something like this:
.page-id-21 .post-title, .page-id-21 post-title a, .page-id-21 .post-title a:visited {color:#000000;}