Hi Marvin
When you install joomla, there is no .htaccess file installed by default.
When your updating the site global configuration ( SITE > GLOBAL CONFIGURATION >
SEO SETTINGS) you'll see a yellow warning advising you to rename the file htaccess.txt that was installed to .htaccess before activating - this is so it has the correct settings for a whole bunch of stuff for securing your install and updating your site urls correctly is enabled.
using your favourite ftp client or the plesk/cpanel with bod, rename your htaccess.txt to .htaccess under httpdocs, ensure the permissions are set to 644 and you should be good to go.
hth