Log in to your WordPress blog as an administrator. Navigate to Plugins → Add New in the left navigation bar. Then search for "Duo Security" and click Install Now for the Duo Two-Factor Authentication plugin.
To install the Duo two-factor plugin without using the WordPress Plugin directory, first download the Duo plugin as a zipped package from WordPress.
In the WordPress console go to Plugins → Add New and click the Upload Plugin button.
Click Choose File and select the duo_wordpress.zip package you downloaded. Click Install Now to upload Duo's plugin to your WordPress site.
Click Activate Plugin after installing the Duo plugin:
After activation, click Settings to configure the plugin.
Copy and paste your integration key, secret key, and API hostname from the Duo WordPress application you created earlier. You may select which WordPress user roles need to authenticate using Duo. For example, you may only require those users with the "Administrator" role to use two-factor authentication, or require all roles to use two-factor.
To fully secure your WordPress site Duo recommends that you disable XML-RPC. However, this will prevent use of offline Weblog clients and the WordPress mobile app.
Click Save Changes to complete configuration.
Open a new browser (or incognito window) and try to log in to your WordPress account. You should be prompted to set up your two-factor authentication. Complete the enrollment process.