Changing URL of site

Hello,

I have created a site and filled it with alot of content but its located on the same domain as where I have wordpress installed. However, this domain is not the site I want to have the site live at. I have tried to changed the “home” field in wp-config.php

define(‘WP_HOME’,’http://www.newsite.com’);
define(‘WP_SITEURL’,’http://www.oldsite.com/wordpress’);

But that doesnt work, it just loads the new domain but with an error message that the page doesnt exist.

Do I have to transfer any files to the new domain for this to work?
Can it really be that simple that I can just enter a new domain and all pages will be moved there and available online?

Please help, thanks.

Dan