Go to Wordpress admin area and click "Plugins" and then "Add New" menu item.
In the right panel (left top) you will see "Upload Plugin" button. Click the button.
Next click the "Choose file" button in right panel (center).
Select zip file of the "Memcached Cloud" plugin located on your hard drive and press "Open".
Click "Install Now" and the zip file will upload to your site.
Now click "Activate" button to activate the "Memcached Cloud" plugin.
We've tested following plugins published by: Redis Labs- uses the wordpress-memcached-backend project (https://github.com/tollmanz/wordpress-memcached-backend), by Zack Tollman