Searching through a database using checkboxes

Hi guys so i am trying to understand what the best way to search through a database using check boxes is. I am new to this and was looking at tutorials etc but cant seem to find anything which will help. I can make a search engine which searchs through my database and returns what i need but i dont get how to do it with checkboxes. For example:

My database contains this:

    MovieName: ...
    Gen1: ... 
    Gen2:... 
    Gen3:... 
    Gen4:... 
etc

Now like i said above i got it to work with a search box where the user can write a simple phase such as action and it will bring up the movies which has action in their genres but i got no idea how to do it with checkboxes.

HTML:

    <form action = "movie.php" method = "post">
        <input type="checkbox" name = "search" value="action" checked> Kale<br>
        <input type="checkbox" name= "search" value="comdey" checked> orange<br>
        <input type="submit" value="Submit">
    </form> 

    <?php echo("$output");?>

My database name TestHere and table is called test. Any help on completing this matter or any advice would be great, if you would like to see my search function i could post that but i dont think it will help with the search function of the checkboxes

Edit : This is a search function i created. Also i know its the old mysql shizzle but this is for a project which i am currently working on and i want it to be using that.

PHP:

$output = '';
//collect 
if(isset($_POST['search'])){
    $searchq = $_POST['search'];

    $query = mysql_query("SELECT * FROM test WHERE movieName LIKE '%$searchq%' OR gen1 LIKE '%$searchq%' OR gen2 LIKE '%$searchq%' OR gen3 LIKE '%$searchq%' OR gen4 LIKE '%$searchq%'") or die("Could not search.");
    $count = mysql_num_rows($query);
    if($count == 0) {
        $output = 'There was mo match!';
    }else{
        while($row = mysql_fetch_array($query)){
            $rN = $row['movieName'];
            $rI1 = $row['gen1'];
            $rI2 = $row['gen2'];
            $rI3 = $row['gen3'];
            $rI4 = $row['gen4'];
            $pic = $row['pix'];

            $output .= '
            <div class="panel panel-default">
                <div class="panel-heading"><b>' . htmlentities($rN, ENT_QUOTES) . '</b></div>
                    <div class="panel-body">
                        <div class="pull-left col-xs-12 col-sm-4">
                            <a href="#">
                                <img class="img-thumbnail img-responsive" <img src="data:image/jpeg;base64,'.base64_encode( $pic ).'"/>
                            </a>
                            <a class="btn btn-success btn-block btnrec" href="#">View Recipe</a>
                        </div>

                        <div class="col-xs-12 col-sm-6 col-md-6">
                            <div class="media-body">
                                <h3 class="media-heading">INGREDIENTS:</h3> ';

for( $i=1; $i < 7; $i++ )
{
    if( ${"rI$i"} )
    {
                $output .= '

                            <div class="food-graph">
                                <span class="food-graph-title">' . htmlentities(${"rI$i"}, ENT_QUOTES) . '</span>
                            </div>

        ';

    }
}

 $output .= '                   </div>
                </div>
            </div>
    <div class="panel-footer">Rating</div>
     </div>
    '; 
        }
    }
    }

Again this works perfectly for a search function, just not sure how i can apply this to a checkbox function :)