On Yoast seo, when you create a new page it gives you the ability to alter titles, etc. This is added by the yoast module. I am writing a plugin, that can have other things attaching to a post. How can I modify the admin panel to add these new option? Thanks John
what you are looking for is call in the WordPress world a MetaBox and just like Yoast SEO you need to use add_meta_box() function to add your own.
there is a great tutorial and class you can use in your plugin at deluxeblogtips.com I would suggest you use that for a starting point.