Note: Creating a copy of an install is the same as moving it, except you don't delete the old version at the end.

Server Move

If you're moving to a whole new server, then you will need to follow these steps:
1) Download a database backup (though your favorite mechanism, be it the WSN backup mechanism or phpmyadmin or cpanel) and then upload it to the new host.
2) Move all the files (download from the old site, then upload to the new site, then delete the old).
3) Edit your config.php file to change your old database connection info to the new info that applies on your new host (presuming that it's different). Also change the $dirurl (directory url) and file path to the attachments directory ($uploadpath) to the new locations if they're changing.
4) If the URL is changing, submit the Settings -> SEO page to get the .htaccess regenerated.

Moving Within the Server

Suppose you have WSN Knowledge Base installed on the base directory of your site, yoursite.com, and you want to move it to yoursite.com/directory.

Follow this process:
1) Go to your settings and change the directory url and upload path listed there to the new location. (Alternately you can modify your config.php to specify them.
2) Move all the files (download from the old directory, then upload to the new directory, then delete the old).
3) If using url rewriting, submit the Settings -> SEO page to get the .htaccess updated.

Note that step 1 is important because if you don't change the url setting before moving you'll end up getting redirected to the old location when logging in to your admin panel. Also note that if your install is already in a subdirectory, you can skip the trouble of downloading and uploading by just renaming the directory to the new name you want.