How do I fix SEO urls with lighttpd?

I want to rewrite my URL from ?p=pagename to a SEO friendly URL like this: /pagename How does url.rewrite works?

I have seen an example like this but haven't figured how it works yet.

url.rewrite = ( "^/(data|install|js|styles)/(.*)$" => "$0", "^/(.*\.php)(.*)$" => "$0", "^/.*(\?.*)" => "/index.php$1", "" => "/index.php" )