1. Login to your WordPress admin dashboard.

2. Under the dashboard menu, hover your mouse on Posts and then click on Categories.

Enter the following details in Add New Category:
Name: Enter your category name such as Computer.
Slug: Enter a slug name or leave this as it is.
Parent: Leave this to None or should you select a category, it will become a sub-category of your chosen category, and the browser will show a URL like hostnali.com/technology/pc
Description: You can leave this as it is.

Now click on the Add New Category button.