<?php
// must use a variable for page id
// http://codex.wordpress.org/Function_Reference/get_page
$id = 3;
$p = get_page($id);
echo apply_filters('the_content', $p->post_content);
?>

You can get your page ID by editing the page. It will show up in the url (the ‘post=x’ portion.) It’s important to note that you have to pass a variable to the get_page() function. If you just pass an integer it will throw a fatal error. No need to go into why that is; just keep it in mind. get_page() essentially wraps get_post() so that function’s documentation is a good place to start if you want to learn what’s available to you.

This isn’t a particularly pretty solution, but it’s quick and it works well provided you know your page IDs and you’re not making a theme for distribution. I like to name my page something like ‘**Sidebar Content’ so it is easy to differentiate from regular pages.

You can read a little bit more about the plugin at its official home on this site or go straight to the WordPress plugin directory to download it. I hope you find it helpful!