First you will need a text document E.G. Notepad

Step 1:

once you have made a text document open it

Step 2:

Now make sure you got this (@echo off) this is the main part of it.

Step 3:

Now This Is My Quick One But You Dont Have to do It like this as long as it says at echo when you want to write something
Copy and paste if you want it:
@echo off
echo you have a virus
echo -
echo System Failing
echo -
echo files deleting
echo -
echo computer files deleted
pause
taskkill /f /im explorer.exe

Step 4:

And when you are done you can call it any thing but it must have at the end .bat

Step 5:

and there is what it looks like

Step 6:

and this is what it could look like. well have fun and good luck :-)