Joomla! 1,5 has a built in function to make your URLs search engine friendly. SEF URLs do not contain ? and a bunch of numbers, instead they are converted to a readable URL that contains hyphens between the words, An example of a SEF URL would be joomla-sef-urls.html all lower case.
To create SEF URLs in Joomla open the Joomla admin in a browser. In the top menu bar go to: Site > Global Configuration.
Open Global configuration. Ther will be three tabs, site – system- server Under the tab site on the far right there is a section SEO Settings. All should be changed to YES.
Now the htaccess.txt file on the root of your Joomla installation must be renamed to .htaccess and re-uploaded to the server via ftp
Your URLs now should look like this: