This is going to be a simple WP Cron tutorial that explains the basic use of WordPress cron, the wp_schedule_event function and it's 3 built in intervals. I'll write a more complex one soon that explains how to add your own intervals, but this is a good starting point:
Practical Code Example
<?php
//Add function to register daily function on WordPress init
add_action( 'init', 'register_daily_cron');
// Function which will register the daily event:
function register_daily_cron() {
// Make sure event hasn't been scheduled already:
if(!wp_next_scheduled('daily_cron')) {
// Schedule the event
wp_schedule_event(time(), 'daily', 'daily_cron');
}
}
?>