redirect from dynamic url to friendly urls

i dont know how to redirect from
w w w.4pcsoft.com/?cat=Audio to http://www.4pcsoft.com/Audio.html

Google index houndreds of dynamic links and i need an 301 redirect with htaccess to friendly link.
i try RewriteRule ^/?cat=(.*) /$1.html [R=301,L] but it not work

10x

 

you're doing it backwards. you need to look for audio.html and then redirect to blah.php?cat=audio

example .htaccess

RewriteEngine on
RewriteRule ^([A-Za-z0-9-_\+]+).html$ index.php?cat=$1

Code (markup):

this should accept (anything).html formatted with chars and _ + or -

eg: poon_and_pie.html
something+else.html
foo-bar.html
foo.html