Add Adsense between post

Hello,

I try to add an adsense block into my wordpress theme template, just after the first post.

I have found a tutorial to do this here : http://www.tamba2.org.uk/wordpress/adsense/

But there’s a problem of syntax or it’s me I don’t understand :

It said to add adsense code :

<?php if ($postnum == $showadsense1) {
echo '
Your adsense code goes here
';
} ?>

<?php $postnum++; ?>

So if I do this I have something like that :

<?php if ($postnum == $showadsense1) {
echo '
<script type="text/javascript"><!--
google_ad_client = "pub-0000000000000";
/* 200x200, date de création 04/05/09 */
google_ad_slot = "000000000";
google_ad_width = 200;
google_ad_height = 200;
//-->
</script>
<script type="text/javascript"
src="http://pagead2.googlesyndication.com/pagead/show_ads.js">
</script>
';
} ?>

<?php $postnum++; ?>

And as you can see the syntax is not correct…

Who could help me please ?