Mod rewrite question

I want to learn how to use the mod rewrite functions provided by wordpress. I started off by making an substitute rewrite for search, but it does not work. any ideeas, as the documentation for the API is poor in details.
thanks 🙂

this is the code:

global $wp_rewrite;
add_action(‘generate_rewrite_rules’, ‘feed_dir_rewrite’);
function feed_dir_rewrite($wp_rewrite) {
$feed_rules = array(
‘mysearch/(.+)/?$’ => ‘index.php?s=$1’,
);

$wp_rewrite->rules = $feed_rules + $wp_rewrite->rules;
}