How to highlight text in elastic search result - codeigniter

hello guys, thanks for helping me before, so now i can explore more about elastic search.

so far, i can manipulate data using elasticsearch. i create new library in my php framework (codeigniter).
after make several data input.
since the best part of elastic is searching (yeah of course....), i wonder to make search feature.

but when i create it, im dissapointed with the result.
unlike kibana, my result didnt show the highlight text of keywords that i input before.

question is :
how to make highlight text in elastic search result

many thanks in return

Did you read the highlighting doc?

yes i read it bro. but the problem is i dont know where to place this code :

    "query" : {...},
    "highlight" : {
        "fields" : {
            **"content" : {}**

since my code in php only like this :
controller :

$product = $this->elasticsearch->searchDocsWithParameter($type, $post);
$result = json_decode(json_encode($product),true);
echo "total took:";
echo $result['took'];    

$x=0; $no=1;
while($x <= $result['_shards']['total']):
echo $no; echo" . ";
echo $result["hits"]["hits"][$x]['_source']['en_question']; 
echo $result["hits"]["hits"][$x]['_source']['en_answer']; 
$x++; $no++;

library :

    public function searchDocsWithParameter($type, $query")
        return $this->call($type . '/_search?' . http_build_query(array('q' => $q)));

i already googling about it, nobody post about how it.
thats why i ask to this forum. pls help me.