Images and CSS not displaying

Hi, I hope someone can help me with a beginner question.

I am trying to create a copy of an existing WordPress site so that I can work on it without affecting the live site. I am completely new to WordPress so I may be missing something obvious.

On my own domain, I have installed wordpress in a directory called /wp and recreated the live site there. The problem is that every page is looking for /images and stylesheets as if they are located in the root directory. I have changed wp-config.php to read as follows:

/** Absolute path to the WordPress directory. */
if ( !defined(‘ABSPATH’) )
define(‘ABSPATH’, dirname(__FILE__) . ‘/wp’);

But this does not seem to have fixed the problem. All of the paths are still looking for assets at the top level without the wp/ subdirectory.

If anyone can offer any advice I would be very grateful! I hope it is something fairly easy to reconfigure. Or if anyone has an easier solution to create a staging version of a site so that it can be worked out without affecting the live site, I would be very interested to read your advice.

Many thanks in advance