It is normally a good practice to create the category you are going to use, before creating posts, however you can always change which category a post appears in later.
To create and view Categories, click Categories on the left hand menu, under Posts.

- The Name of the category is what people will see directly, if you choose to show a category in a menu for instance.
- The Slug is normally a shortened version of the name, which may appear in the address bar.
- Parent allows you to select if this is a sub category of another category.
- The Description may appear on a page dedicated to the category, depending on your theme.
Click Add New Category to add the category to the list.
The Name is the only field that is required, in order to create a category. The Slug will be filled automatically if it is empty.
To edit a category, click on the name of the category, and the same 4 options will show for you to edit. Click Update when you have finished making your changes.