Hi,
When the custom action is triggered, you can store it in a new table or in an array in the user_meta table and use this function wnbell_update_user_count( $user_id ) to increment the notification count.
To see this notification in the box, you can use these filter hooks:
wnbell_user_notifications_array : to sort the notifications with the other user notifications before outputting them
wnbell_user_notifications_output : returns the html output of a notification item you’ll see in the notification box
To change the css for seen notifications, you can use these hooks:
wnbell_add_unseen : when a user clicks on a notification, you can add its id to an array of viewed notifications
wnbell_seen_data : to get the array of viewed notifications id for a particular user to use for the output