To add a Categories widget (for categorizing the posts on the website) to your WordPress website, login to your WordPress dash board and proceed as follows:

• From the left hand side pane, select Appearance.
• Click on Widgets.
• Now, the widgets window opens up that lists all the available widgets on your WordPress.
• Search and locate the widget named Categories.
• Click on the widget (Categories) and a dropdown menu appears which lists the places where you can place this widget on your website.
• Select one place (Ex. Left Sidebar) from the list by clicking on it.
• Now, click Add Widget button located under the same list, to add it to your website.

(If you do not find Categories widget in your widgets, then follow the steps outlined under, “How to add a new widget/plugin to my website?” and then follow the steps mentioned above.)