This article describes how to install plugins and themes in WordPress.
Installing a Theme from the WordPress.org repository
The first thing you need to do in your WordPress dashboard is go to “Appearance > Themes” to go to the themes page.

On the Themes page there are two places where you can click to add a new theme. The first one is a button right next to the “Themes” title of the page, or if you hover over the big plus sign below the installed themes you will see it highlighted in blue, click there to add a theme.

You will immediately get a window full of thumbnails with the “Featured” themes from the WordPress.org repository. You can do a search in the box at the right side of the page if you know the name of the theme you are looking for or you can click on already made searches like “Popular”, “Latest”, “Favorite” and “Feature Filter”.
You can hover over each theme image to either view the details or a preview of the theme or to install it immediately.

Below you can see the Theme Preview of the Kadence theme.

Once you have previewed the theme you can go ahead and install it. Then Click the blue button to “Activate” it.

Use the “Feature Filter” to find themes according to their specific characteristics like “Three columns” or “Footer widgets” or a theme suitable for a “Blog” or a “Portfolio”.

Installing a Theme from a File Upload
In order to install a theme you have purchased or have in your computer you start the same way going to “Appearance > Themes”, then click the “Add new” button. This will bring the “Featured” repository themes but also a button right next to the title “Add Themes” which says “Upload Theme”. This will bring a screen with the option to search for the file in your computer.

Click on “Choose File” to search for the theme file in your computer (must be a .zip file – a compressed file with all the theme items inside). When you have chosen your theme file, click on the “Install Now” button to proceed with the installation.

After the theme has been installed you need to activate it to make it the default theme.

When you go back to the themes page you will see the first theme is the “Active” theme, the one you just installed and activated. From here you can click on that blue “Customize” button or see if the theme has settings in the Dashboard menu (There will be a menu item with the theme’s name for example “Divi” or “Enfold”)

Installing a Plugin from the WordPress.org repository
In order to install a plugin, whether from the WordPress.org repository or a file from your computer you alway start from “Plugins > Add New”.

In the screen that shows up you can search for a specific type of plugin or search by name. In the demo I searched for the keyword “backup” and got all these responses. I was looking for a specific plugin called Duplicator and I found it at the bottom right of the page. In order to install it I clicked on the “Install Now” button.

Once the plugin has been installed you need to manually activate it by clicking on the blue button that says “Activate”. Then you can use your new plugin.

You will be redirected to the plugins page and see that your plugin is installed and activated. Most plugins will create a new option in the sidebar menu with the name of the plugin, in this case it says “Duplicator” but some plugins have their settings pages hidden in the Settings menu item or other areas in the dashboard menu.
If you have installed a plugin and can’t find its name in the sidebar, you can try going to the Plugins > All Plugins page and see what is listed underneath the plugin name, there is usually a link to settings.

Installing a Theme from a File Upload
Like I mentioned in the step before in order to upload a new plugin you need to go to “Plugins > Add New”. The next screen will give you a button “Upload Plugin” that will show the “Choose File” option. Click on that option and look for your file in your computer. It should be a .zip compressed file. Then click the “Install Now” button.

Once the plugin has been installed you need to manually activate it. WordPress doesn’t do it automatically because you might not want to have it active immediately (the plugin might change things in your WordPress installation and you might not be ready for it). The plugin I installed in the demo is “Duplicate Page”.

This plugin doesn’t need to have a menu entry as it works on the posts and pages, so in order to see it in action you go to the posts or pages and hover over the post/page title.

Conclusion
Installing themes and plugins is easy to do, what’s not so easy is trying to NOT install too many of them. When we are starting out we might try many different themes to see what our site will look like and the same with plugins. After you have finished testing out themes and plugins try to always delete the unused themes/plugins so that your WordPress.org site is not bogged down with unneeded code (it could make your site slower).
Thank you for reading.