Detect session/cookie variable in wordpress to prevent access to documents

<?php
@session_start();

If (!array_key_exists(‘authed’, $_SESSION))
{
     include ‘not_authed.inc’;
     exit();
}

// go about your business.

?>

and i’m trying to add that to this:

<?php

function checkValues($value)
{
     // Use this function on all those values where you want to check for both sql injection and cross site scripting
     //Trim the value
     $value = trim($value);

    // Stripslashes
    if (get_magic_quotes_gpc()) {
        $value = stripslashes($value);
    }

     // Convert all &lt;, &gt; etc. to normal html and then strip these
     $value = strtr($value,array_flip(get_html_translation_table(HTML_ENTITIES)));

     // Strip HTML Tags
     $value = strip_tags($value);

    // Quote the value
    $value = mysql_real_escape_string($value);
    return $value;

}   
mysql_connect ("mysql.*****.com", "****","$*****")  or die (mysql_error());
mysql_select_db ("***********");

$term = checkValues($_REQUEST['val']);
$term = mysql_real_escape_string($term);

$sql = mysql_query("select * FROM patient_db WHERE id_number = '$term'");


if($row = mysql_fetch_array($sql)) {
    echo "<img src="******" class='leftfloat' border=0>";
    echo '<p>';
    echo '<br /> ID Number: '   .$row['id_number'];
    echo '<br /> Name: '        .$row['Name'];
    echo '<br /> Exp. Date: '   .$row['exp_date'];
    echo '<br /> DOB: '         .$row['dob'];
    echo '</p>';
    //echo "<a href='******' title='Printer Friendly Version' alt='Printer Friendly Version'><img src="*****" class='rightfloat' border=0 height=33 width=33></a>";
} else {
    echo "<img src="*****" height=50 width=50 class='leftfloat' border=0>";
    print "<h1>USER ID <br/>NOT FOUND</h1><br />";
    print "<strong>OOPS!! THIS COULD BE AN ERROR</strong><br />";
    print "<br />";
    print "<div>*****</div>";
}

?>