Hello @stratuspg,
To make the category available make sure to assign the post you have created in the categories of your choice. Then the categories will be available in the option “Select Category:“.
Also, to integrate with Facebook and Google requires higher code customization.
So if you wish then you can hire our professional developer.
To hire a developer please refer to below-given link:
https://themepalace.com/hire-a-customizer
Hope this helps.
Best Regards!!