Customizing post titles in sidebar?

Hi there, so I’d like to have a list of all my posts in the sidebar listed by the title of the posts. And I found the solution below, but really don’t know what the wp_get_archives is or where it is. I’m sure this is such a newbie question, but I’m well…a newbie.

Thanks!

Solution:
Part of helping your visitors navigate your site is to point them towards specific posts and archives. Your most recent posts and archives can be displayed in a variety of ways in your sidebar. The WordPress Classic and Default Themes showcase the archives by month:

<li id=”archives”><?php _e(‘Archives:’); ?>

<?php wp_get_archives(‘type=monthly’); ?>

Using the wp_get_archives() template tag, you can customize this list in a variety of ways. Let’s say you want to list the last 15 posts you’ve written by their title. Replace the type=monthly as follows:

<?php wp_get_archives(‘type=postbypost&limit=15’); ?>