Creating a Category in WordPress
In order to have your blog in a decent structure and ease your visitors' navigation throughout your posts and pages, you should categorize your news. A new category is created from the Manage menu, Categories section.

Please, note: Deleting a category does not delete posts from that category, it will just set them back to the default category Uncategorized.
In order to move a post from one category to another, please, click on Posts under the Manage menu item. Click Edit

And then just switch the ticked category. Please, press Save when you are ready with the changes
