I've created a custom page which displays some data from the wordpress d/b and a form with action set to another php file, my_processForm.php. that file validates the form data and also access the wordpress d/b to get data and update data.
The custom page works fine but in the action file, I get an error for every line that uses a wordpress function such as
get_header(); (Call to undefined function get_header)
$table_prefix = $wpdb->prefix; (Trying to get property of non-object)
How can I get access to these functions and objects?