Tabbed content for WordPress sidebar

Follow that tutorial and use below code for specific category recent post where tutorial used un order list content.

<ul>
    <?php $recent = new WP_Query("cat=1&showposts=10"); while($recent->have_posts()) : $recent->the_post();?>
        <li><a href="https://wordpress.stackexchange.com/questions/35006/<?php the_permalink() ?>" rel="bookmark">
        <?php the_title(); ?>
        </a></li>
    <?php endwhile; ?>
</ul>

Change cat id and number of post as per your choice.