So the first instruction is telling you to upload the casino.php into the same folder your forum is in. That way you have a an address to go to. Mine is
http://www.thedarktower.com/palaver/casino.php
"palaver" is my forum folder--Put the "casino" folder in there as well
After that you will load files to folders already existing. So every thing in the downloaded AdminCP folder goes into your existing AdminCP folder in your forum folder.
Everything in the Includes folder from the download-goes into Includes existing on your server.
So you are just moving files into existing folders at that point. Get it all done and you should be good to go if you have uploaded the product.xml