Rewriting index.php?cat=0 to /cat/

[wazimm1]

so far I've read at least 20 post on mod rewrite and how I can change this http://www.newpornlist.com/index.php?cat=0 to>>>> http://www.newpornlist.com/cat/

well, I have had no success yet....... Can you please give a hand on this? Many say it's easy but .... I'M JUST NOT GETTING IT YET