WordPress.org

The easy way:

1. Go to the 'Plugins' 'Add new' menu in WordPress
2. Search for 'Australian Internet Blackout'
3. Find the plugin in the list returned (it should be the first one) and click 'Install'
4. Activate the plugin through the 'Plugins' menu in WordPress
5. The protest screen will now be displayed to people visiting your blog.

The hard(er) way: (If you prefer to install things yourself.)

1. Download the Australian Internet Blackout plugin
2. Unzip the plugin
3. Upload the australian-internet-blackout directory to the /wp-content/plugins/ directory
4. Activate the plugin through the 'Plugins' menu in WordPress
5. The protest screen will now be displayed to people visiting your blog.