How do I keep only specific Pages on nav bar

Hello,

I’m trying to set up my Word Press theme to list only specific pages on the nav bar. For my nav bar, I’m using code for a drop down menu that I found on a site, https://tinyurl.com/627w4t . The nav bar works perfectly. However, how do I set it up to only include the pages I want?

I did some research and was told to use

wp_list_pages('title_li=&include=4,37,22')

However, when I use it with my code, it messes up my nav bar. Here’s my code. Any idea of what I could try.

<ul id="nav">
<?php wp_list_pages('title_li=&depth=1'); ?>
</ul>   

<?php if($post->post_parent)
$children = wp_list_pages("title_li=&child_of=".$post->post_parent."&echo=0"); else
$children = wp_list_pages("title_li=&child_of=".$post->ID."&echo=0");   

if ($children && is_page()) { ?>
<ul id="subnav">
<?php echo $children; ?>
</ul>
<?php } else { ?>
<?php } ?>

Can someone help me?