THIS TECHNIQUE NO LONGER WORKS.
Firstly you want to go to the start menu and type SHUTDOWN -I and press enter and the program should open
Step 1: Beginner Hacker Tutorial Ep.2: Remotely Shutting Down a Website
Now, your going to need your targets IP so refer to Beginner Hacker Tutorial Ep.1.
Press the add button and type in the IP of your target.
Step 2: Beginner Hacker Tutorial Ep.2: Remotely Shutting Down a Website
First change the action to shutdown if it isn't already.
Then change the reason to security issue and press OK