How to install a WordPress plugin
Installing a WordPress plugin manually is easy and simply process.
Install a Plugin manually using WordPress Plugin Upload
Some WordPress plugins are not listed in Free WordPress plugin directory and cannot be installed from WordPress plugin directory. But WordPress comes with plugin upload installer.
First download the plugin from source website (This file should be in .zip format) Then from WordPress admin dashboard open Plugins > Add New > Upload Plugin to upload this .zip file.
Click on upload plugin button to reveal Plugin select form. Click on Choose File button and select the plugin file.
After selecting plugin file click on install now button to start plugin upload. WordPress will now upload and unzip this plugin file on your WordPress website which can be activated through Plugins page.
After the upload is complete you will a message like this on this page click on Activate Plugin button to start using this plugin.
After activation you have to configure your plugin settings according to documentation of that plugin.