Admin panel in php

I am struggling with redirecting to a admin panel page in php. I have tried 2 different codes without success. I have no idea what I am doing, as I don't have a good solid understanding of the fundamentals of php. But I think I'm getting close, any help appreciated. Thankyou in advance.

user_level is the entry in the database , 2 is for members and 3 for admin. error logs posted at the bottom.

  $username = $_SESSION['username'];
            while($row = mysqli_fetch_object($conn))
            {
                $admin = $row->user_level;

        }
        if ($admin == 3) { header('Location: admin.php'); 

    }

code 2

$username = $_SESSION['username'];
$query_level = mysqli_query("SELECT user_level FROM members WHERE username = '$username' ");
$run_level = mysqli_fetch_array($conn, $query_level);
$row = mysqli_fetch_assoc($run_level);
    if ($row == 3) {
        header('Location: admin.php');
    } 

[26-Jun-2016 09:03:09 Australia/Brisbane] PHP Warning: mysqli_fetch_object() expects parameter 1 to be mysqli_result, object given in /public_html/login/memberpage.php on line 46 [26-Jun-2016 09:03:09 Australia/Brisbane] PHP Notice: Undefined variable: admin in /public_html/login/memberpage.php on line 51

26-Jun-2016 09:05:06 Australia/Brisbane] PHP Warning: mysqli_query() expects at least 2 parameters, 1 given in /public_html/login/memberpage.php on line 46 [26-Jun-2016 09:05:06 Australia/Brisbane] PHP Warning: mysqli_fetch_array() expects parameter 1 to be mysqli_result, null given in /public_html/login/memberpage.php on line 47 [26-Jun-2016 09:05:06 Australia/Brisbane] PHP Warning: mysqli_fetch_assoc() expects parameter 1 to be mysqli_result, null given in /public_html/login/memberpage.php on line 48