I'm trying to add extra search functions for a plug-in, in most themes there is a search.php file that I edit to add the search function to include the plug-in's table in the database.
I want to add the following to the search query

PHP Code:

if(is_search()) {
    $search = $wp_query->get('s');
    $keywords = preg_replace('/\+/',' ',$search);
    if (function_exists ('ngg_get_search_pictures')) {  // function from functions.php
        $nggpictures = ngg_get_search_pictures($keywords, ''); // put the number of pictures by row you want, if you don't want "4"

        if ($nggpictures) {
            echo "<h2>Pictures</h2>";
            echo $nggpictures;    
        } 
    }
} 


see searchform.php