从前端上传多个图像到帖子

I have referred to this link multiple image upload from frontend in wordpress for adding multiple images to a post. The code is working i.e., the images are uploading to media library but not showing in posts can you please let me know whether I have to create a field in Post to store them. If yes how?

Code for submitting a a post:

 <div class="new-post">
<form action="" method="post" enctype="multipart/form-data">
    <div class="form-group">
        <label for="title">Title :</label><br />
        <input class="form-control" type="text" id="title" value="" tabindex="1" size="20" name="title" minlength="5" required />
    </div>
    <div class="form-group">
        <label for="description">Description :</label><br />
        <textarea class="form-control" id="description" tabindex="3" name="description" cols="50" rows="6" minlength="30" required></textarea>
    </div>
    <div class="form-group">
        <?php 
        $args_drop = array(
            'show_option_none'   => 'Category',
            'hide_empty'         => false,
            'include'            => '26, 27, 29, 34, 33',
            'tab_index'          => 3,
            'taxonomy'           => 'category',
        );
        wp_dropdown_categories($args_drop);
        ?>
    </div>


    <div class="form-group">
        <label for="file">Image 2 :</label>
        <input type="file" name="custom_1" value="Custom Field 1 Content" />
    </div>

    <div class="form-group">
        <label for="postPhoto1">Photo 1 :</label>
        <input type="file" name="upload_attachment[]" id="postPhoto1">
    </div>

    <div class="form-group">
        <label for="postPhoto1">Photo 2 :</label>
        <input type="file" name="upload_attachment[]" id="postPhoto2">
    </div>   


    <input type="submit" value="Submit" tabindex="6" id="submit" name="submit" />

    <input type="hidden" name="post_type" id="post_type" value="domande" />
    <input type="hidden" name="action" value="post" />
    <?php wp_nonce_field( 'new-post' ); ?>
</form>

Php for processing form :

if(is_user_logged_in() == true) {

// Check if the form was submitted
if( 'POST' == $_SERVER['REQUEST_METHOD'] && !empty( $_POST['action'] )) {

// Do some minor form validation to make sure there is content
if (isset ($_POST['title'])) { 
    $title =  $_POST['title'];

} else { 
    echo 'Please enter a title';
}
if (isset ($_POST['description'])) { 
    $description = $_POST['description']; 
} else { 
    echo 'Please enter the content'; 
}

$custom_field_1 = $_POST['custom_1'];

// Add the content of the form to $post as an array
$post = array(
    'post_title'    => $title,
    'post_content'  => $description,
    'post_category' => array($_POST['cat']),

    'post_status'   => 'publish',         // Choose: publish, preview, future, etc.
    'post_type'     => 'work'  // Use a custom post type if you want to
);
$pid = wp_insert_post($post);  // Pass  the value of $post to WordPress the insert function    

if ( $_FILES ) {
    $files = $_FILES['upload_attachment'];
    foreach ($files['name'] as $key => $value) {
        if ($files['name'][$key]) {
            $file = array(
                'name'     => $files['name'][$key],
                'type'     => $files['type'][$key],
                'tmp_name' => $files['tmp_name'][$key],
                'error'    => $files['error'][$key],
                'size'     => $files['size'][$key]
            );

            $_FILES = array("upload_attachment" => $file);

            foreach ($_FILES as $file => $array) {
                $newupload = insert_attachment($file,$pid);
            }
        }
    }
}
$category_filter = array($_POST['cat_filter']);

}

Now the question is that through this code I am able to upload the images but where do I save them in the post. like a featured image has a section in post where it gets saved or how do I retrieve them to a page?

Thanks