How to create WordPress categories
To create new categories in WordPress, you need to access the Posts -> Categories page first.
On the left side of the page you will see a tab that allows you to create categories. Fill in the category name, its slug (will be used in the category URLs) and the Add New Category button. For the purpose of this tutorial we will make a new category named Family posts.
That’s it, your first category is ready. Now, let’s make a sub-category of the Family posts one named Nephews. Fill in a name and slug the way you did with the first category but this time select Family posts as parent for the new category. Then, press Add New Category once more to save thew new sub-category.