First off, only
one line of code is mIRC, I'm guessing you added that in, and its
Everything else is PHP. You can Google random lines of code
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true); if you want, and you will find PHP references.
If you have seen others run it, that's because they are running it on a PHP server/machine or whatever they are called.
NOT mIRC.