Unordered List Category with PHP

I’m working on a site and would like to incorporate all the posts from a category in the left side menu bar. http://earthlit.com/

I managed to get them in place with a line of php code in sidebar.php.

Line of code being used: <?php wp_get_archives( array( ‘type’ => ‘postbypost’, ‘limit’ => 30, ‘format’ => ‘custom’ ) ); ?>

But I need to have the list to have one post per line like an unordered list.

Could someone help me figure out what I need to do?