如何在wordpress中按年份和月份排序的嵌套列表中添加帖子缩略图

我的档案页面中有一个列表,显示了先按年份排序,然后按月份排序的帖子。如何将文章缩略图与文章标题一起添加?我不太了解php和wordpress。这是列表的代码。希望有人能帮助我。

<div id="post-<?php the_ID(); ?>" <?php post_class(); ?>>               
<ul id="archivio"> <!--anni-->
<?php
$years = $wpdb->get_col("SELECT DISTINCT YEAR(post_date) FROM $wpdb->posts WHERE  post_status = 'publish' ORDER BY post_date DESC");

foreach($years as $year) : ?>
<li><?php echo $year; ?>
        <ol class="mesi"> <!--mesi-->
        <?php $months = $wpdb->get_col("SELECT DISTINCT MONTH(post_date) FROM $wpdb->posts WHERE post_status = 'publish' AND YEAR(post_date) = '".$year."' ORDER BY post_date DESC");

        foreach($months as $month) : ?>

        <li>
        <?php echo date( 'F', mktime(0, 0, 0, $month) );?>
            <ul class="post"> <!--post-->
            <?php  $theids = $wpdb->get_results("SELECT ID, post_title FROM $wpdb->posts WHERE post_status = 'publish' AND post_type = 'post' AND MONTH(post_date)= '".$month."' AND YEAR(post_date) = '".$year."' ORDER BY post_date DESC");

            foreach ($theids as $theid): ?>

                <li><a href="<?php bloginfo('url'); ?>?p=<?php echo $theid->ID; ?>"><?php echo $theid->post_title; ?>
        </a></li>


            <?php endforeach; ?>

            </ul>                
        </li>

        <?php endforeach;?>

        </ol>
    </li>

    <?php endforeach; ?>
</ul>
</div>