Plugin Dev Getting Started

Hi all.

So, this is my first real plugin. It won't be for public distribution. I want to migrate the membership info from a custom website to BuddyPress.

First step, add an admin page under the Settings menu. Here's what I've got so far:

add_submenu_page(
'menu-settings', // parent_slug
'LPHS Migration', // page_title
'LPHS Migration', // menu_title
'manage_options', // capability
'lphsmigration', // menu_slug
'lphs_migration_page' // function
);

What I'm getting when I refresh the admin page is:

Fatal error: Call to undefined function add_submenu_page() in /Users/alfred/Sites/lphs2.0/wordpress/wp-content/plugins/lphsmigrate/lphsmigrate.php on line 15

So, I figure this is something that needs to be put in a function which is then called by some hook. Little help?

Thanks,
- AAA