Session and GD

Hello-
I use session and it works correctly,but when I want to use GD at the same page it shows an error message as follow:

Warning: Cannot add header information - headers already sent by

How do I use session and gd at the same page?

Thanks for your helping and sorry for my poor English.

this is no problem, ju just need to use the GD before sending output.

<?php
session_start();
session_register("Name");
$Name = "Set Name";
gd_image_create();
blah blah;
?>

<head>
blah blah

Yeah...
It works.. 🙂
Thanks for your helping... ^_