ถ้าเราจะส่งค่าที่เลือกจาก checkbox แล้วส่งไปกับ pop up เราจะส่งไปยังไง

<form name="frmMain" action="" method="get">
<table width="60%" border="1" cellspacing="1" cellpadding="3">
  <tr>
    <td>ID</td>
    <td>Name</td>
    <td>&nbsp;</td>
  </tr>
<?
require("mysql.inc.php");
$query=mysql_query("select * from customer");
while($k=mysql_fetch_array($query)){
?> 
  <tr>
    <td><input type="checkbox" name="id[]" id="id" value="<? echo $k['CustomerID']; ?>"></td>
    <td><? echo $k['Name']; ?></td>
    <td>&nbsp;</td>
  </tr>
<?
}
mysql_close($link);
?> 
</table>
<input type="submit" value=" OK " onClick="window.open('pop_up2.php?id='+document.getElementById('id').value,'popup','toolbar=0,scrollbars=1,height=200,left = 200,top = 200')" />
</form>

<form name="frmMain" action="" method="post"><center>
<?
for($k=1; $k<count($_POST['id']); $k++){
echo $_POST['id'][$k];
}
?> 
<input type="button" name="btnClose" value="Close" OnClick="window.close();">
</center></form>

<script>
function popup(name){
   var win = window.open('', name, 'toolbar=0,scrollbars=1,height=200,left = 200,top = 200');
   return true;
}
</script>
<form name="frmMain" action="pop_up2.php" method="POST" target="popup" onsubmit="return popup(this.target)">
<table width="60%" border="1" cellspacing="1" cellpadding="3">
  <tr>
    <td>ID</td>
    <td>Name</td>
    <td>&nbsp;</td>
  </tr>
<?
require("mysql.inc.php");
$query=mysql_query("select * from customer");
while($k=mysql_fetch_array($query)){
?> 
  <tr>
    <td><input type="checkbox" name="id[]" id="id" value="<? echo $k['CustomerID']; ?>"></td>
    <td><? echo $k['Name']; ?></td>
    <td>&nbsp;</td>
  </tr>
<?
}
mysql_close($link);
?> 
</table>
<input type="submit" value=" OK "  />
</form>

<center>
<?
for($k=0; $k<count($_POST['id']); $k++){   // PHP ค่า index เริ่มจาก 0 นะครับไม่ใช่ 1
echo $_POST['id'][$k];
}
?> 
<input type="button" name="btnClose" value="Close" OnClick="window.close();">
</center>