sidebar – trying to install widgits

Hi Here is my sidebar code. I want to install this random picture widget but when I choose widgets from the menu it says my theme doesn’t support sidebars. I don’t know what that means.

<?php include (TEMPLATEPATH . ‘/searchform.php’); ?>

<div id=”sidebar”>
<h3>Category</h3>
<ul class=”ul-cat”>
<?php wp_list_categories(‘show_count=1&title_li=’); ?>

<h3>Archives</h3>
<ul class=”ul-archives”>
<?php wp_get_archives(‘type=monthly’); ?>

</div>
<!–/sidebar –>

Here’s the error I get.

No Sidebars Defined

Can somebody please help steer me in the right direction? Please. I appreciate it.

Thank you.
2bit