Add Facebook messenger to several users Wordpress

Hi. I have a WP install with Classima Theme [login to view URL] I want to add Facebook messenger to all stores. So every store has the FB mess icon so buyers can contact their FB directly. Because i have several stores the individual FB page ID has to be added to the backend of each store. So what i need is: 1. Add a field for FB page ID so the stores can put that in with other store info. 2. Facebook Mess impimented as the docs say: [login to view URL] I DO NOT want any bids from developers that havent done this before. If you bid you should be certain that you can do it.