Rajesh Soni on "Add custom fields"

You can use get_post_meta() function to retrieve the value of the custom field.

Example usage:

<?php
$custom_field_name = get_post_meta($post->ID, 'custom_field_name', true);
?>
<a href='check-details.php?custom_field=<?php echo $custom_field_name; ?>'>Check details</a>

http://codex.wordpress.org/Function_Reference/get_post_meta
http://codex.wordpress.org/Custom_Fields