Changing Ip to url – wp-config

I have a single wwordpress installation at an ip address which I now need to change to the finished domain name.

I know I need to point the domain to the Ip and then change on the wordpress side. The simplest seems to be changing wp-config going by this support article.
http://codex.wordpress.org/Changing_The_Site_URL

by adding this to wp-config

define(‘WP_HOME’,’http://example.com’);
define(‘WP_SITEURL’,’http://example.com’);

Does my domain name go into both fields above or does wp-home become the domain , and then the site url is my existing ip address?
or do I change both fields to the domain name?

Any info appreciated. Never done this bit before/