The goal here is to make a list of posts in the sidebar that show a number of recent posts. There will be a button you can click which will replaces those links to recent posts with older posts, AJAX style. You can keep clicking the button and keep getting older and older posts. On this site, we currently show 5 recent posts. So this little section shows the 5 posts after that, then clicking the button once will show 5 more older than that, and so on.
WordPress has the ability to easily password protect the content of any Post or Page. Right over by that big juicy blue "Publish" button, there is an option for Visibility. Click edit, and you have the option to make it password-protected and set a password.
On blogs that like to share snippets of code like this one, it is common to use the <pre> tag to wrap the code so that the spacing/indenting is maintained and long lines do not wrap. While this is desirable behavior, it can be undesirable to have those un-wrapped lines break out of their containers awkwardly and overlap other content.
I previously posted on how to include jQuery in your WordPress theme the Right Way. That is, to use the
wp_register_script function to register the script first. It's literally a one-liner in your header.php or functions.php file, but by default, it loads the internal version of jQuery that ships with WordPress.
If you want, you can just download jQuery, put it on your server and link to it from your header.php file in the <head> section. But that can cause you grief. For one thing, some plugins use the jQuery library, and they are going to load it as well. This can cause problems. How was your plugin to know you already had it loaded?