I can't believe you actually clicked here, but if you want to know then i will tell you.
First off, this isn't a real virus, it won't do any damage to anyones computer, just turn it off.
So first thing we want to do is go to you desktop, right click and select,
New -> Shortcut.

Then a box will pop up fill it in as such.

the -s means Initiate Shutdown, the -t signals to shutdown in the specified Time in seconds.
I forgot to mention, if you want to put a message in there, put a -c after the time, i forgot to do that inthe picture.
Then after you can have notes that will be displayed to the user. Make sure that they are in ""'s. You can have prank messages such as, "thankyou for downloading Virus heat, you computer will shutdown in (howeverlong)."
So here's an example

I have renamed it Internet Explorer on the next screen after you press next so i will change the icon to the ie one.
Then when you open it you get, this screen

And you will notice that you can't close it.
The onlyway to close it in to press the start button > run then type: shutdown -a to abort it. but don't tell them that.