每个用户插入输入数据

I'm attempting to design a page that I can manually enter player names per user and send that into my database table.

Each user has 13 different players and they are the blue smudges on the image I uploaded. There player's will be entered in the inputs I have under neath of them.

I am having difficulty figuring out how I can INSERT a player into my database per user. So if I was under the first user in the 4th block/input, and clicked submit, I would want that to be assigned to that user with the 4th pick.

Here is my database structure...

playersByUser
CREATE TABLE `playersByUser` (
 `id` int(11) NOT NULL AUTO_INCREMENT,
 `userid` int(11) DEFAULT NULL,
 `playername` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL,
 `ordering` tinyint(4) DEFAULT NULL,
 PRIMARY KEY (`id`),
 KEY `userid` (`userid`),
 CONSTRAINT `playersByUser_ibfk_1` FOREIGN KEY (`userid`) REFERENCES `users` (`id`)

) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci

Here is the code for what I am trying to do.

        <form action="" method="POST"> 
<?php 
$con = mysqli_connect("localhost", "", "", ""); 
if (mysqli_connect_errno()) { 
    printf("Connect failed: %s
", mysqli_connect_error()); 
    exit(); 
} 
$stmt = mysqli_query($con,"SELECT up.ordering, u.username, up.playername 
FROM users AS u  
INNER JOIN playersByUser AS up ON u.id = up.userid 
WHERE u.id = $userid 
ORDER BY up.ordering"); 

if(isset($_POST['Add Player'])){ 
//Variables to post in the bind_param 
$insert_user_id = $_POST['user_id']; 
$insert_player = $_POST['playername']; 

$stmt2 = $con->prepare("INSERT INTO playersByUser (user_id, playername) VALUES (?, ?)"); 
if ( false===$stmt2 ) { 
    die('Player Insert prepare() failed: ' . htmlspecialchars($con->error)); 
} 
if(!$stmt2->bind_param('is', $insert_user_id, $insert_player)) { 
    // Check errors for binding parameters 
        die('Player Insert bind_param() failed: ' . htmlspecialchars($stmt2->error)); 
    } 
if(!$stmt2->execute()) { 
        die('Player Insert execute() failed: ' . htmlspecialchars($stmt2->error)); 
    } 
} 
$playerArray = array(); 

//$userid => $insert_player 
//); 

while($row = mysqli_fetch_array($stmt)) { 
    $playersArray[$row['userid']=$row['playername']; 
?> 
    <div class="draftResultsWrap"> 
        <div class="inline"> 
        <?php echo "<div>" . $row['firstname'] . " " . $row['lastname'] . "</div>"; ?> 
        </div> 
            <input type="text" name="<?php echo playerArray[] ?>" class="draftBorder" value='1'/> 
            <input type="text" name="<?php echo playerArray[] ?>" class="draftBorder" value='2'/> 
            <input type="text" name="<?php echo playerArray[] ?>" class="draftBorder" value='3'/> 
            <input type="text" name="<?php echo playerArray[] ?>" class="draftBorder" value='4'/> 
            <input type="text" name="<?php echo playerArray[] ?>" class="draftBorder" value='5'/> 
            <input type="text" name="<?php echo playerArray[] ?>" class="draftBorder" value='6'/> 
            <input type="text" name="<?php echo playerArray[] ?>" class="draftBorder" value='7'/> 
            <input type="text" name="<?php echo playerArray[] ?>" class="draftBorder" value='8'/> 
            <input type="text" name="<?php echo playerArray[] ?>" class="draftBorder" value='9'/> 
            <input type="text" name="<?php echo playerArray[] ?>" class="draftBorder" value='10'/> 
            <input type="text" name="<?php echo playerArray[] ?>" class="draftBorder" value='11'/> 
            <input type="text" name="<?php echo playerArray[] ?>" class="draftBorder" value='12'/> 
            <input type="text" name="<?php echo playerArray[] ?>" class="draftBorder" value='13'/> 
        </div> 
<?php 
} 
?> 
            <button type="submit" method="POST" name="Add Player">Submit Changes</button> 
        </form>

Could anyone provide some insight on what I am doing wrong or how to do this?