Here’s an interactive tutorial
** Best experienced in Full Screen (click the icon in the top right corner before you begin) **
https://www.iorad.com/player/2289553/How-To-Add-New-Category-To-A-Post—WordPress–EN-0022-
7 STEPS
1. The first step is to open Dashboard and click All Posts
2. Choose a post and click Edit
3. Click + Add New Category
4. Type the name of your New Category
5. Click Add New Category
6. Click Uncategorized to exclude your post from that category
7. Click Update